Re: when was the first time that Standard Temperature and Pressure was used?

I do not know when the name 'STP' was first used. But I can pin down when 
the idea was first used to a time between about 1812 and 1825, to a 
country, France, and probably to the scientist Gay-Lussac.

In the years immediately after 1800, measurement of quantities in chemical 
reactions was becoming very important. There was a debate going on about 
whether chemical reactions proceeded in fixed or variable proportions. 
Dalton brought out his atomic theory, which was very controversial, and 
depended critically on reacting masses of different materials. But earlier 
theories of equivalents (proposed by the German chemist Richter) and 
affinities (by the French chemist Berthollet) also depended on reacting 
masses. But masses of gases are very hard to measure accurately. They weigh 
much less than whatever container they are held in. And corrections must be 
made for buoyancy due to the air that is displaced by the vessel that 
contains the gas.

Gay-Lussac worked extensively with gases. And he advocated working with 
volume rather than pressure. He found that gases combined in fixed and very 
simple volume ratios in chemical reactions. In particular he found that

1 volume of oxygen combined with 2 volumes of hydrogen to produce water
1 volume of ammonia combined with 1 volume of hydrogen chloride to produce 
ammonium chloride
2 volumes of carbon monoxide combined with 1 volume of oxygen to produce 
carbon dioxide

The law that gases combine in very simple volume ratios like this is still 
known as Gay-Lussac's law.

But there is a very big problem in working with gas volumes. Gas volumes 
change by large amounts with changes in pressure. So the volume of a sample 
of gas will change by 2 or 3 percent between a fine day or a stormy day at 
Dewitt, and by about 20 percent if you take it from Dewitt to Denver. The 
relationship between gas pressures and volumes was discovered by Boyle 
(Anglo-Irish) and Mariotte (French) independently in the early 1660s. (And 
is therefore known as "Boyle's Law" or "Mariotte's Law" depending on your 
cultural orientation!). Gas volumes also change quite a lot with 
temperature, discovered and quantified by Charles (French) in the 1780s 
("Charles' Law"), and established more accurately by Gay-Lussac in the 
1810s.

What this means is that there is not a lot of use in specifying a gas 
volume as a measure of the amount of gas unless you also specify the 
temperature and pressure that the volume of gas is measured at. And gas 
volumes were at the heart of Gay-Lussac's work.

The pressure part of STP is a fairly obvious standard. It refers to 1 
atmosphere or 76 cm of Mercury. The metric measure points to Napoleonic 
France as the source. If the English had been working in this area we might 
have had to live with some standard in inches of mercury or pounds per 
square inch!! :-)

The 0 deg C is perhaps a little less obvious. It may have referred to the 
typical Paris lab temperature for an outsider like Marie Curie, but Gay-
Lussac was an establishment figure whose lab would have been more 
comfortable than that! ;-)

It is, however, an easily fixed temperature -- freezing point of water -- 
and has another advantage. A small correction has to be applied to mercury 
column pressure measurements to allow for expansion of the mercury with 
temperature. 0 deg C is also the temperature at which mercury column 
pressures need no correction. Even so, it is a bit unfortunate that the 
standard temperature for STP is an uncomfortably cool one, and, more 
importantly, that it does not conform to the 25 deg C standard used for so 
many other chemical quantities.