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The problem with this article is that it goes in depth into related issues and this is not required. The density of water is not an issue to be discussed in any detail here. I (Paul) am proposing a major re-write which will say everything there is to be said about relative density directly, with links to air and water and density and other articles too. Therefore, the article will be MUCH SHORTER. Paul Beardsell 04:15, 18 November 2006 (UTC)
I suggest that the material relating to the kidney be moved to Kidney or to Kidney function or, if we must, to Specific gravity (kidney). The kidney is a machine (a living machine, an organ) and an important one but there are numerous machines (and organs) for which the specific gravity of a solution or suchlike is important. This article should say what RD / SG is and describe that BUT discussion of machine / organ function and medical treatment details / engineering maintenance instructions should be moved to the page about the organ / machine. Material should not be duplicated at WP - it should be linked to. Move imminent. What say you? Paul Beardsell 23:33, 19 January 2007 (UTC)
I've cut the material. I'll put it here in case anyone wants to rescue it for inclusion in a more appropriate article. Paul Beardsell 21:22, 22 January 2007 (UTC)
I went ahead and moved the text to Specific gravity (kidney). There are also several articles on WP that link readers to specific gravity for further information on urinary specific gravity. I'll try to fix as many as I can. Jay † Litman 14:55, 2 February 2007 (UTC)
relative densities are not about liquids (only). I will be removing the para that goes on about sinking and floating "in the reference [substance]" as if the reference could only be a liquid, as if the other substance is not itself another liquid, as if the the other substance would not dissolve! Too clever. Paul Beardsell 07:08, 29 January 2007 (UTC)
If man would possess any sort of "logic" a whole new term would be derived "Gravitational Density" and both pages would be place under that and the whole goofy debate would be put to rest. Good grief. And by the way, Gravitational Density is what keeps each planet their exact distance from the sun. Must see EinsteinGravity.com —Preceding unsigned comment added by 68.148.82.185 ( talk) 19:43, 19 March 2011 (UTC)
I think this page ought to be moved to Specific Gravity. The term relative density has meanings other than Specific Gravity - i.e. the denominator is not always the density of water. SG, however, is always relative to water. Toiyabe 19:07, 13 March 2006 (UTC)
I've written a short description of SG. SG is specific in that it intrinsically refers to the standard substance as water. To speak of just relative density, leaves the question of which standard substance used unanswered. The article on Relative density also seems to cover topics which to me seem better explained and covered elsewhere. Pae_nor Oslo, Norway, 18:48, 14 February 2007
This article is in need of some cleanup. The article is inconsistent, inaccurate and somewhat verbose. E.g it states that relative density is both similar and the same as Specific gravity. Also, it is inaccurate to state that "quantify the buoyancy between two materials": Bouyancy is, simply stated, an upward force as experienced by an object wholy or partly immersed in a surrounding fluid (gas or liquid), i.e substances incapable of sustaining shear forces. Calculation of SG can be done irrespective of units used, as long as the units used are consistent, i.e. don't divide slugs/ft3 with kg/m3... When it comes to Specific gravity (SG) i still feel that the article I wrote is more accurate w.r.t SG and should not be redirected. Pae_nor 09:52, 15 February 2007 (UTC)
since density of water is (approximately) - I am no physics expert but I had been taught that the metric system was designed around the physical characteristics of wtaer - meaning the density of water would be precisely as stated and not approximate. Am I wrong? SauliH 18:29, 27 February 2007 (UTC)
I did a recent semi-overhaul of the page. But I'm not an expert, I'm just an engineering college graduate who got A's in his physics classes and math classes. I know the power of using natural units and I appreciate using unitless dimensions. Hence the large section for the unitless properties of RD. Also, my physics proff. wanted us to demonstrate the hydrometer problem shown. I figured it was important enough to be encyclopedic. I've got a second proof, showing that a hyperbolic cross sectional area would create a linear relationship between displacement and change in RD, but decided it was not encyclopedic enough to warrant placing it on here. Since it required the use of calculus, I doubt most readers would understand it as well. (Also, I'm not quite an expert, as I've said before.)
If anyone has grammar issues, spelling issues, etc... change up the page. I'm not a grammar expert, and I don't know how to program this math code for beans. If anyone thinks the math isn't important enough to warrant placing here, let me know and I'll just put it on my talk page. I don't have any source for the proof I listed concerning the hydrometers, but I did cite other wiki pages which had sources and used basic algebra for my proof. Let me know if you think this info is usefull or not. -- Markozeta 01:35, 13 March 2007 (UTC)
Please see comments at Scientific peer review/Relative density (March 2007) Could this and other highly technical articles have a Basic, or Simple, paragraph, or a few, near the top? Because all I was looking for was to compare how dense water is to iron [as was discussed on a program about the universe]. It seems related to the issue that reality is very thin, it's practically a ghost world. 24.165.104.209 ( talk) 06:15, 15 February 2013 (UTC)
While I understand the insignificance of units in the solution to a RD calculation, I think it would be more appropriate for the article to be consistent with the unit's it uses to describe RD. Presently, the movement between the SI and Imperial systems (namely in the 'Specific Gravity' section) may be confusing for those not familiar with the topic, and it may also create unnecessary difficulties for those who are attempting to make such calculations. It may also be wise to do so purely in the interest of maintaining a set standard, the SI. Psydexzerity 13:50, 25 June 2007 (UTC)
Can we just have a plain specific gravity article for those who need it? Just an explanation of what specific gravity is and how to measure it? At a pinch, where the measurement could be useful? This article is full of overly technical bollocks and is hence fairly useless. And it has no mention of pycnometer measurement of sg. Last time someone tried to do the right thing and separate the two they were merged again. I am happy to assist in creating an sg article (I am a chemist and know little about its application outside chemistry so would not volunteer to write it by myself).-- 218.214.57.78 04:52, 12 July 2007 (UTC)
I think the use of these terms has changed over the years. The latest Macquarie Dictionary in Australia for relative density redirects to specific gravity. The definition of specific gravity states that it is the density relative to that of a standard, with the standard being water for liquids and solids and hydrogen or air for gases. We need to address this in detail looking at different definitions in different places at different times and have everything referenced. Does anyone have a number of different science or physics dictionaries to hand? -- Bduke 23:10, 30 July 2007 (UTC) I also think that the terms are different. Specific gravity is density of substance by density of water at 4°C. But there is no mention of temperature in relative density. Density of water is maximum at 4°C. But in physics, density of water is always taken as 1 g/cm^3. So, I am confused. -- Utsav Raj king 18:00, 24 November 2019 (IST)
I am tempted to remove some of the lengthy mathematical derivations in this article and just retain the key steps, concepts and results. At the moment it looks more like a textbook than an encyclopedia article. Does anyone object to this? 86.133.48.159 ( talk) 02:34, 6 March 2008 (UTC)
Under the section Measurement, the second image showing an equation seems to introduce specific numeric values that come out of nowhere. I think these should be trimmed off, leaving the first bit, but wanted to ask if I was missing something. Thoughts? Edgehawk ( talk) 15:19, 4 September 2010 (UTC)
Specific gravity and relative density cover almost exactly the same material. The either need to be made more distinct or merged. Not that long ago it was tried to merge it under relative density, but that failed. I am hoping that the reason it failed was because there wasn't enough discussion before hand. So lets form a consensus and get this thing done ;) . TStein ( talk) 17:57, 22 October 2010 (UTC)
Specific gravity is the more widely recognized term. However, relative density is more appropriate.I agree the topics should be merged under Specific Gravity. ISAnerd ( talk) 20:06, 2 November 2010 (UTC)ISANerd
I support the merging to specific gravity as well. I see little difference between the two, and in my studies I've almost always heard it referred to as specific gravity. While I agree "relative density" makes more sense in terms of words, we should use the most common term per WP:COMMONNAME. 71.113.43.168 ( talk) 00:30, 28 December 2010 (UTC)
I am happy with the situation as is appears on the "relative density" page. The term "relative density" is usually used in the resources industry. http://en.wikipedia.org/wiki/User:Johnhvisser 17:44, 19 March 2011 (Perth) Johnhvisser — Preceding unsigned comment added by Johnhvisser ( talk • contribs)
The term "Relative density" is used in European Pharmacopoeia and all nationals pharmacopoeias. The text explains also methods as they are mentioned in European Pharmacopoeia. I did not meet the term specific gravity in pharmaceutical sciences. — Preceding unsigned comment added by 158.195.64.181 ( talk) 15:35, 3 August 2011 (UTC)
make coherent set of density, relative density, etc
Even in outer space, where there is no gravity, there is still mass,
meaning that a heavier object needs more force to be accelerated ;
So term 'specific gravity' is a bit misleading,
what is meant is 'specific density of mass'.
Word 'specific' means that it is a property of a material,
but is in practice used as if it means 'relative to density of water'.
A material that has specific density 1 has absolute density 1000 kg/m3,
so these terms should not be mixed up.
I think it would be best to have
which explains that this is relative to density of water (which is 1000 kg/m3),
and links to 'density' and 'water' pages.
that mentions that this term is in common use,
and is also known as 'specific gravity' and 'specific weight'
but really means 'relative (mass) density',
and links to 'relative density' page.
Thusly organizing these articles seems not difficult, more work would be needed for removal of off-topic content, such as, in 'specific gravity', description of a flask that is said to be used for measuring specific gravity, while it really only allows to measure off a precise volume. Ofcourse this flask can be weighed, but it is still a tool for volume measurement ; to measure density directly one would need to measure buoyancy. Siwardio ( talk) 11:00, 27 August 2011 (UTC)
Typo or in need of greater explanation:
I do not see the validity of a simple division used as was referenced:
"Taking into account different sample and reference temperatures we note that while SGH2O = 1.000000 (20°C/20°C) it is also the case that SGH2O = 0.998203/0.998840 = 0.998363 (20°C/4°C)."
Followed by:
"Here temperature is being specified using the current ITS-90 scale and the densities[4] used here and in the rest of this article are based on that scale. On the previous IPTS-68 scale the densities at 20 °C and 4 °C are, respectively, 0.9982071 and 0.9999720 resulting in an SG (20°C/4°C) value for water of 0.9982343."
Again the numbers do not agree. 0.999 362 260
0.998 207 1 / 0.999 972 0 = 0.998 235 050 The average is 0.999 089 55
Was there an interpolation done based on some criteria, a formula used, different numbers used from some other reference, or are these typographic errors?
As for an error in significant digits used, I do not care if they are just typo. But if another process is involved, I would like to know what process was used to generate the value for water of 0.998 234 3
Jamesbdunn (
talk) 14:36, 30 December 2012 (UTC)
pycnometer deserves a separate article. Editors should consider moving the Pycnometer section to a new page 182.69.180.130 ( talk) 12:38, 16 March 2023 (UTC)
![]() | This ![]() It is of interest to the following WikiProjects: | ||||||||||||||||||||
|
![]() | The contents of the Specific gravity page were merged into Relative density on 4 February 2020. For the contribution history and old versions of the redirected page, please see its history; for the discussion at that location, see its talk page. |
![]() | Please note the following Archived Discussions & Related Talk Pages:
|
The problem with this article is that it goes in depth into related issues and this is not required. The density of water is not an issue to be discussed in any detail here. I (Paul) am proposing a major re-write which will say everything there is to be said about relative density directly, with links to air and water and density and other articles too. Therefore, the article will be MUCH SHORTER. Paul Beardsell 04:15, 18 November 2006 (UTC)
I suggest that the material relating to the kidney be moved to Kidney or to Kidney function or, if we must, to Specific gravity (kidney). The kidney is a machine (a living machine, an organ) and an important one but there are numerous machines (and organs) for which the specific gravity of a solution or suchlike is important. This article should say what RD / SG is and describe that BUT discussion of machine / organ function and medical treatment details / engineering maintenance instructions should be moved to the page about the organ / machine. Material should not be duplicated at WP - it should be linked to. Move imminent. What say you? Paul Beardsell 23:33, 19 January 2007 (UTC)
I've cut the material. I'll put it here in case anyone wants to rescue it for inclusion in a more appropriate article. Paul Beardsell 21:22, 22 January 2007 (UTC)
I went ahead and moved the text to Specific gravity (kidney). There are also several articles on WP that link readers to specific gravity for further information on urinary specific gravity. I'll try to fix as many as I can. Jay † Litman 14:55, 2 February 2007 (UTC)
relative densities are not about liquids (only). I will be removing the para that goes on about sinking and floating "in the reference [substance]" as if the reference could only be a liquid, as if the other substance is not itself another liquid, as if the the other substance would not dissolve! Too clever. Paul Beardsell 07:08, 29 January 2007 (UTC)
If man would possess any sort of "logic" a whole new term would be derived "Gravitational Density" and both pages would be place under that and the whole goofy debate would be put to rest. Good grief. And by the way, Gravitational Density is what keeps each planet their exact distance from the sun. Must see EinsteinGravity.com —Preceding unsigned comment added by 68.148.82.185 ( talk) 19:43, 19 March 2011 (UTC)
I think this page ought to be moved to Specific Gravity. The term relative density has meanings other than Specific Gravity - i.e. the denominator is not always the density of water. SG, however, is always relative to water. Toiyabe 19:07, 13 March 2006 (UTC)
I've written a short description of SG. SG is specific in that it intrinsically refers to the standard substance as water. To speak of just relative density, leaves the question of which standard substance used unanswered. The article on Relative density also seems to cover topics which to me seem better explained and covered elsewhere. Pae_nor Oslo, Norway, 18:48, 14 February 2007
This article is in need of some cleanup. The article is inconsistent, inaccurate and somewhat verbose. E.g it states that relative density is both similar and the same as Specific gravity. Also, it is inaccurate to state that "quantify the buoyancy between two materials": Bouyancy is, simply stated, an upward force as experienced by an object wholy or partly immersed in a surrounding fluid (gas or liquid), i.e substances incapable of sustaining shear forces. Calculation of SG can be done irrespective of units used, as long as the units used are consistent, i.e. don't divide slugs/ft3 with kg/m3... When it comes to Specific gravity (SG) i still feel that the article I wrote is more accurate w.r.t SG and should not be redirected. Pae_nor 09:52, 15 February 2007 (UTC)
since density of water is (approximately) - I am no physics expert but I had been taught that the metric system was designed around the physical characteristics of wtaer - meaning the density of water would be precisely as stated and not approximate. Am I wrong? SauliH 18:29, 27 February 2007 (UTC)
I did a recent semi-overhaul of the page. But I'm not an expert, I'm just an engineering college graduate who got A's in his physics classes and math classes. I know the power of using natural units and I appreciate using unitless dimensions. Hence the large section for the unitless properties of RD. Also, my physics proff. wanted us to demonstrate the hydrometer problem shown. I figured it was important enough to be encyclopedic. I've got a second proof, showing that a hyperbolic cross sectional area would create a linear relationship between displacement and change in RD, but decided it was not encyclopedic enough to warrant placing it on here. Since it required the use of calculus, I doubt most readers would understand it as well. (Also, I'm not quite an expert, as I've said before.)
If anyone has grammar issues, spelling issues, etc... change up the page. I'm not a grammar expert, and I don't know how to program this math code for beans. If anyone thinks the math isn't important enough to warrant placing here, let me know and I'll just put it on my talk page. I don't have any source for the proof I listed concerning the hydrometers, but I did cite other wiki pages which had sources and used basic algebra for my proof. Let me know if you think this info is usefull or not. -- Markozeta 01:35, 13 March 2007 (UTC)
Please see comments at Scientific peer review/Relative density (March 2007) Could this and other highly technical articles have a Basic, or Simple, paragraph, or a few, near the top? Because all I was looking for was to compare how dense water is to iron [as was discussed on a program about the universe]. It seems related to the issue that reality is very thin, it's practically a ghost world. 24.165.104.209 ( talk) 06:15, 15 February 2013 (UTC)
While I understand the insignificance of units in the solution to a RD calculation, I think it would be more appropriate for the article to be consistent with the unit's it uses to describe RD. Presently, the movement between the SI and Imperial systems (namely in the 'Specific Gravity' section) may be confusing for those not familiar with the topic, and it may also create unnecessary difficulties for those who are attempting to make such calculations. It may also be wise to do so purely in the interest of maintaining a set standard, the SI. Psydexzerity 13:50, 25 June 2007 (UTC)
Can we just have a plain specific gravity article for those who need it? Just an explanation of what specific gravity is and how to measure it? At a pinch, where the measurement could be useful? This article is full of overly technical bollocks and is hence fairly useless. And it has no mention of pycnometer measurement of sg. Last time someone tried to do the right thing and separate the two they were merged again. I am happy to assist in creating an sg article (I am a chemist and know little about its application outside chemistry so would not volunteer to write it by myself).-- 218.214.57.78 04:52, 12 July 2007 (UTC)
I think the use of these terms has changed over the years. The latest Macquarie Dictionary in Australia for relative density redirects to specific gravity. The definition of specific gravity states that it is the density relative to that of a standard, with the standard being water for liquids and solids and hydrogen or air for gases. We need to address this in detail looking at different definitions in different places at different times and have everything referenced. Does anyone have a number of different science or physics dictionaries to hand? -- Bduke 23:10, 30 July 2007 (UTC) I also think that the terms are different. Specific gravity is density of substance by density of water at 4°C. But there is no mention of temperature in relative density. Density of water is maximum at 4°C. But in physics, density of water is always taken as 1 g/cm^3. So, I am confused. -- Utsav Raj king 18:00, 24 November 2019 (IST)
I am tempted to remove some of the lengthy mathematical derivations in this article and just retain the key steps, concepts and results. At the moment it looks more like a textbook than an encyclopedia article. Does anyone object to this? 86.133.48.159 ( talk) 02:34, 6 March 2008 (UTC)
Under the section Measurement, the second image showing an equation seems to introduce specific numeric values that come out of nowhere. I think these should be trimmed off, leaving the first bit, but wanted to ask if I was missing something. Thoughts? Edgehawk ( talk) 15:19, 4 September 2010 (UTC)
Specific gravity and relative density cover almost exactly the same material. The either need to be made more distinct or merged. Not that long ago it was tried to merge it under relative density, but that failed. I am hoping that the reason it failed was because there wasn't enough discussion before hand. So lets form a consensus and get this thing done ;) . TStein ( talk) 17:57, 22 October 2010 (UTC)
Specific gravity is the more widely recognized term. However, relative density is more appropriate.I agree the topics should be merged under Specific Gravity. ISAnerd ( talk) 20:06, 2 November 2010 (UTC)ISANerd
I support the merging to specific gravity as well. I see little difference between the two, and in my studies I've almost always heard it referred to as specific gravity. While I agree "relative density" makes more sense in terms of words, we should use the most common term per WP:COMMONNAME. 71.113.43.168 ( talk) 00:30, 28 December 2010 (UTC)
I am happy with the situation as is appears on the "relative density" page. The term "relative density" is usually used in the resources industry. http://en.wikipedia.org/wiki/User:Johnhvisser 17:44, 19 March 2011 (Perth) Johnhvisser — Preceding unsigned comment added by Johnhvisser ( talk • contribs)
The term "Relative density" is used in European Pharmacopoeia and all nationals pharmacopoeias. The text explains also methods as they are mentioned in European Pharmacopoeia. I did not meet the term specific gravity in pharmaceutical sciences. — Preceding unsigned comment added by 158.195.64.181 ( talk) 15:35, 3 August 2011 (UTC)
make coherent set of density, relative density, etc
Even in outer space, where there is no gravity, there is still mass,
meaning that a heavier object needs more force to be accelerated ;
So term 'specific gravity' is a bit misleading,
what is meant is 'specific density of mass'.
Word 'specific' means that it is a property of a material,
but is in practice used as if it means 'relative to density of water'.
A material that has specific density 1 has absolute density 1000 kg/m3,
so these terms should not be mixed up.
I think it would be best to have
which explains that this is relative to density of water (which is 1000 kg/m3),
and links to 'density' and 'water' pages.
that mentions that this term is in common use,
and is also known as 'specific gravity' and 'specific weight'
but really means 'relative (mass) density',
and links to 'relative density' page.
Thusly organizing these articles seems not difficult, more work would be needed for removal of off-topic content, such as, in 'specific gravity', description of a flask that is said to be used for measuring specific gravity, while it really only allows to measure off a precise volume. Ofcourse this flask can be weighed, but it is still a tool for volume measurement ; to measure density directly one would need to measure buoyancy. Siwardio ( talk) 11:00, 27 August 2011 (UTC)
Typo or in need of greater explanation:
I do not see the validity of a simple division used as was referenced:
"Taking into account different sample and reference temperatures we note that while SGH2O = 1.000000 (20°C/20°C) it is also the case that SGH2O = 0.998203/0.998840 = 0.998363 (20°C/4°C)."
Followed by:
"Here temperature is being specified using the current ITS-90 scale and the densities[4] used here and in the rest of this article are based on that scale. On the previous IPTS-68 scale the densities at 20 °C and 4 °C are, respectively, 0.9982071 and 0.9999720 resulting in an SG (20°C/4°C) value for water of 0.9982343."
Again the numbers do not agree. 0.999 362 260
0.998 207 1 / 0.999 972 0 = 0.998 235 050 The average is 0.999 089 55
Was there an interpolation done based on some criteria, a formula used, different numbers used from some other reference, or are these typographic errors?
As for an error in significant digits used, I do not care if they are just typo. But if another process is involved, I would like to know what process was used to generate the value for water of 0.998 234 3
Jamesbdunn (
talk) 14:36, 30 December 2012 (UTC)
pycnometer deserves a separate article. Editors should consider moving the Pycnometer section to a new page 182.69.180.130 ( talk) 12:38, 16 March 2023 (UTC)