400 British Association for the Advancement of Science. 



tive, and that for chabasie positive, and from certain crystals of 

 chabasie including an excess of silica, which is a substance plesio- 

 morphous with chabasie. (Dr. Thompson gave it as his opinion 

 that the phaenomena in question arise from the admixture of two 

 distinct species of chabasie, one of which includes soda and the 

 other lime.) 



Professor Johnston stated verbally the results of his analysis of 

 the single and double iodides of gold, results which he found to 

 correspond generally with those already obtained for the chloride. 



Professor Graham gave an account of some recent researches 

 which he has published in reference to the constitution of certain 

 compounds as far as respects their constituent water. He illus- 

 trated his views by sulphuric acid, with 1 and 2 atoms of water, 

 by oxalic acid with 1 and 3 atoms of water, and by nitric acid 

 containing 1 and 4 atoms of water. Other compounds were also 

 adduced, such as oxalate of magnesia, which contains two atoms of 

 water, or that which may be considered as the water of crystalliza- 

 tion of oxalic acid. The oxalate, binoxalate, and quadroxalate of 

 potash, and several other saline compounds were also brought for- 

 ward in explanation of his views. 



Anhyd.oxal.a..(C + C) 



Oxal. water.... (C-f-C)H 



Oxal. acid H(C+C)2H 



Oxal, potash. ..K(C + C)H 



Binox. pot.....K('C+C)H+(C+C)2H 2 



Quadrox.pot...k.(C-fC)H+(C4-C)2H + H(C-fC)H 2 

 He then drew attention to ammonia, which he considered as fre- 

 quently performing the function of water in saline compounds ; a 

 view which he impressed upon the Section by drawing attention to 

 the composition of the sulphate and of two distinct ammoniurets of 

 copper. 



On a new method of testing the presence of Muriatic Acid in Hydro- 

 cyanic Acid. By Professor Geoghegan. 



This proceeding is essentially preliminary to the adoption of the 

 usual modes of determining the strength of any given specimen of 

 this agent. The insoluble compounds into which the chlorine of 

 muriatic acid enters, and by the formation of which chemists usually 

 recognise its presence, are known to resemble, in many respects, 

 those to which cyanogen gives rise when combining with the same 

 bases. The method proposed by Dr. Geoghegan is founded on the 

 property which the double salt of the iodide of potassium and bi- 

 cyanide of mercury possesses of being decomposed by acids, and 

 then producing biniodide of mercury. This compound, which ha9 



