1817.] during the Year 1816. 21 
From this table it appears that alcohol and sulphuret of carbon 
experience the same degree of dilatation. This, as Gay-Lussac 
has shown, depends upon the equal density of their vapours. He 
shows that - 
Alcohol at.... 78°41° produces 488°3 its volume of vapour at 100° 
Sulph. of carb. 46°60..,..... 491°] 
RM a poke TONE: waits v0 285°9 
Water :..,. 10000... >... .;1683°1 
Gay-Lussac promises speedily to renew this interesting subject. 
(Ann. de Chim. et Phys. ii. 130.) 
2. Heat evolved by Combination.—It was an opinion entertained 
by Dr. Irvine that whenever two bodies unite together, a quantity of 
heat is evolved. ‘This opinion was founded chiefly upon mixtures 
of sulphuric acid and water, and alcohol and water. Upon these 
mixtures Dr. Irvine appears to have founded a great part of his 
peculiar doctrines respecting heat. It was observed that in all these 
cases the density of the mixture was greater than the mean. Hence 
it was concluded that whenever two bodies unite so that the density 
increases, heat is evolved; but when the density diminishes, heat 
is absorbed. Gay-Lussac has lately published several facts which 
he considers as inconsistent with this doctrine. (Ann. de Chim. et 
Phys. ii. 214.) Most of these facts were previously known. They 
are as follows :— 
(1.) A saturated solution of nitrate of ammonia, at the tempera- 
ture of 61°, and of the density 1-302, was mixed with water in the 
proportion of 44°05 to 33°76. ‘The temperature of the mixture 
sank 8°9°; but the density at 61° was 1°159, while the mean den- 
sity was only 1°151. 
(2.) On adding water to the preceding mixture in the proportion 
of 33°64 to 39°28, the temperature sank 3°4°, while the density 
continued 0'003 above the mean. 
Other saline solutions present the same result, though none to so 
great a degree. 
(3.) The chloride of azote gives out heat and light when decom- 
posed, and reduced to the two simple bodies—chlorine and azote. 
(4.) Lodide of azote likewise gives out heat and light when re- 
duced into iodine and azote. 
(5.) Euchlorine detonates at a temperature below 212°, and 
gives out heat and light when reduced into chlorine and oxygen. 
3. Division of Fahrenheit’s Scale-—My readers will have perused 
with interest some curious particulars respecting Fahrenheit’s ther- 
mometrical scale printed in the Annals, viii. 26, for which I am 
obliged to an anonymous correspondent. The paper in question 
having made its appearance so recently, 1 conceive it to be unne- 
cessary to give any details from it here. 
4. Dr. Marcet’s Method of producing a violent Heat.—In the 
Annals, ii. 99, Dr. Marcet published a method of producing a very 
violent heat, It consisted in passing a current of oxygen gas through 
