1368 



.Dr. Thomas Thomsons Experiments on the 



atom of water. This will be made apparent by the following 

 table : 



Specific Gravity 



Acid. 



Water. 



Water. 



By Expe- 

 riment. 



1-7837 

 1-6588 

 1-5593 

 1-4737 

 1-4170 

 1-3730 

 1-3417 

 1-3105 

 1-2845 



By Cal- 

 culation. 



7114 

 6783 

 5807 

 5000 

 4251 

 3805 

 3430 

 3169 

 2889 



Difference. 



+ 0-0723 



— 0-0195 



— 0-0214 



— 0-0263 



— 0-0081 



— 0-0075 



— 0-0013 



— 0-0064 

 -0-0044 



The expansion is a maximum when an atom of acid com- 

 posed of (1 atom acid + 4 atoms water) unites with an atom 

 of water. It amounts to ^th of the whole. The least 

 takes place when an atom of acid composed of (1 atom acid 

 + 7 atoms water) unites with an atom of water. It 

 amounts only to n^^ of the whole. 



3. Specific heats of various Atomic Compounds of Sulphuric 

 Acid and Water. 

 The method which I employed to determine the specific 

 heats of a compound of 1 atom sulphuric acid with from 1 

 to 10 atoms water, was this. I procured a thin elipsoidal 

 flask capable of holding about 26 cubic inches of any liquid. 

 It terminated in a narrow neck constituting its mouth. To 

 this a perforated cork was fitted, through which a ther- 

 mometer passed, so that its bulb was very nearly in the 

 centre of the flask, while the whole scale was without the 

 mouth. This flask was placed on a wooden circle which 

 grasped it about two inches from the bottom, while all the 

 rest of the flask was free, and surrounded only by the 

 atmosphere. The stand was fixed on a table near a window 

 at the western extremity of a large laboratory, at a great 

 distance from any fire, and only two individuals were pre- 

 sent to manage the observations. 24 cubic inches of each 

 liquid were put into the flask. It was then either by means 

 of a spirit lamp or a sand bath raised to a temperature 

 80° higher than the air of the room, and the time which 

 elapsed, while the thermometer sunk the first 40 of these 



