592 DR MACVICAR ON THE LAW OF VOLUMES OF AERIFORMS 



metrical as ClNa as a nucleus, in a molecule of water of the type X X^.^X, viz., AQ 

 AQ^2^Q which gives about 1 per cent, of oil of vitriol. The next hydrate is when 

 we have a particle of water on each pole only, AQSaqSAQ, which gives about 

 7 per cent, of oil of vitriol. And this forms spontaneously in a damp atmosphere. 

 In hydrosulphuric acid we have S^ the tetratom, Avith H on each pole ; condens- 

 able under great pressure. 



Sulphydric acid, ^^^'^ = |^^^ =1-09. Forced Expt. about -9. 



In sulphurous acid we have S^ partitioned as in sulphuric acid, giving as the 

 product of combustion of sulphur the element SO, heteropolar, and capable both 

 of the dodecatomic and icosatomic molecule ; also condensable only under 

 pressure. 



Qii -^(80)12(80)20 16x12 + 16x20 __ „ ,^ ,^. 

 Sulphurous acid, ^^ ^-^f-^ — ij» — ^ = 1-58. Forced Exp. 1-45. 



Resembling sulphurous acid in the dissymmetry of its element is chlorhydric 

 acid, HCl. But its weight is greater and its volume larger, the icosatom as is 

 most usual having double the volume of the dodecatom. 



The most stable hydrate, that into which both weaker and stronger acids 

 resolve themselves by boiling, has for its authorised formula CIH + 16aq. Doubling 

 as usual, we obtain 2ClH + 32aq, or 2ClHaq + 30aq, i.e., lO(OHaqHO), leading to 

 the construction of the fine dodecatom, 



^^ aqHCl(OHaqHO)i,ClHaq ^ 9 + 37 + (27xl0) + 37 + 9 ^.^..^^^ Expt. Mil. 



The formula of nitric acid NO. HO when doubled, gives also a dodecatom. 

 But all its constituents are so bent upon the aeriform state, that the icosatom 

 cannot be constructed till the molecule is loaded with aq, as by continued boil- 

 ing. And even then it is so tender, that the discordant results of chemists 

 indicate a differentiated liquid, or a liquid struggling for stability by differen- 

 tiation. But the tetrahedron or octohedron is decided. Thus, taking the usual 

 formula, — 



„^ . , ., (NO,HO)„ 54 + 9x8 , _. -r, . ^ ^^ 



Nitnc Acid ^ f— -^z=: -— = l-5o. Expt. 155. 



AQ 324 ^ 



