90 NON-METALS AND THEIR COMBINATIONS. 



Sulphuric acid is a very strong, bibasic acid, which expels or 

 displaces most other acids; its salts are known as sulphates. 



The diluted sulphuric acid, Acidum sulphuricum dilutum, is a 

 mixture of 1 part of acid and 9 parts of water. 







Tests for sulphuric acid and sulphates. 



1. Barium chloride produces a white precipitate of barium 

 sulphate, insoluble in all acids: 



H 2 SO 4 + BaCl 2 = BaSO 4 + 2HC1. 



"2. Soluble lead salts (acetate of lead) produce a white pre- 

 cipitate of sulphate of lead. 



Antidotes. Magnesia, carbonate of sodium, chalk, and soap, 

 to neutralize the acid. . Stomach pump must not be used. 



Sulpho-acids. Whilst but two oxides of sulphur exist in the 

 separate state, there are a large number of sulpho-acids known. 

 They are: 



Hydrosulphuric acid, H 2 S. 

 Hydro-sulphurous acid, H 2 SO 2 . 

 Sulphurous acid, H 2 S0 3 . 

 Sulphuric acid, H 2 SO 4 . 

 Hyposulphurous acid, H 2 S 2 O 3 . 

 Hyposulphuric acid, H 2 S 2 6 . 

 Trithionic acid, H 2 S 3 6 . 

 Tetrathionic acid, H 2 S 4 Q 6 . 

 Pentathionic acid, H 2 S 5 6 . 



The last four members of this series are known as polythionic 

 acids ; they are merely of scientific interest. 



Hyposulphurous acid, H 2 S 2 3 , is of interest in some of its salts, 

 which are known as hyposulphites. The acid itself is not 

 known in the separate state, because it decomposes into sulphur 

 and sulphurous acid when attempts are made to liberate it from 

 its salts. 



Hydrosulphuric acid, H 2 S = 34 (Sulphuretted hydrogen, Hydrogen 

 sulphide}. This compound has been mentioned as being lib- 

 erated by the decomposition of organic matter (putrefaction) 



