Atomic Volume and Specific Gravity, ^S&t 



acid, as pointed out by Kane. The atomic weight of this 



compound, divided by its specific gravity, is ,.n^o = 75*2j 



which is not far from 72'0 or 9x8, considering that the re- 

 sult remains uncorrected for expansion ; this gives a volume 

 of IS'O or 9 X 2 for muriatic acid. The acid which possesses 

 a constant boiling-point and distils over unchanged has a spe- 

 cific gravity of 1*094, and contains 19'19 per cent, of absolute 

 acid, according to Davy, and 20*44 per cent, according to 

 Thomson. The mean of their results indicates the acid to 



1 80*47 

 contain 16*4, or nearly 16 atoms of water. Now , ^., , 

 ' •' 1*094 



= 165, which is not far from 162, the volume of 9x18, ma- 

 king for the volume of muriatic acid in strong solutions 18*0 

 or 9 X 2, a result the same as that obtained by the last cal- 

 culation. These results, and that given in a previous section, 

 along with the fact that hydrochloric acid gas has twice the 

 volume of steam, leave no doubt that muriatic acid affects two 

 volumes ; and converting the liquid into the solid volume, we 

 have a volume of 22*0 or 11 x 2 as the atomic volume of solid 

 muriatic acid. By contrasting this volume with the experi- 

 mental results on the magnesian chlorides, we find a very 

 great similarity. 



Chloride of Hydrogen, volume 22*0 or 11 x 2 



Cobalt ... 22*2 



Magnesium ... 22*1 



Calcium ... 22*4 



Copper ... 22*0 



Mercury ... 22*0 



In dilute solutions muriatic acid affects only one volume, 



and this has been shown to be also the case with chlorides of 



copper and cobalt. Whether nitrate of water and nitrate of 



a magnesian oxide possess the same volume it is difficult to 



decide. Nitrate of water in the acid of specific gravity 1*42 



seems to affect four volumes, and this acid, HO, N05,-f-3HO 



is constituted on the same type as CuO, NO5 + 3HO; yet 



90'2 63 



Y^j^ — "^ — 7y which gives four volumes for HO, NO5, while 



nitrate of copper certainly does not possess more than three 

 volumes. Nitrate of water calculated on weak acids has 

 three volumes ; but there being no good fixed point upon 

 which to make the calculation, we must leave at present this 

 point undetermined. 



An important question now arises as to the truth of the 

 supposition that two atoms of a magnesian metal are equal to 



Phil. Mag. S. 3. No. 183. Siippl. Vol. 27. 2 M 



