SULPHURIC ACID. 



331 



in the furnace as in the illustration, and the receivers, B, containing a 

 little sulphuric acid, are firmly fixed to them. The oily brown product 

 fumes in the air, and is called " fuming sulphuric acid," or Nordhausen 

 acid. Sulphuric acid is very much used in chemical manufactures, and the 

 prices of many necessaries, such as soap, soda, calico, stearin, paper, etc., 

 are in close relationship with the cost and production of sulphur, which also 

 plays an important part in the making of gunpowder. The manufacture of 

 the acid is carried on in platinum stills. 



Sulphuretted hydrogen, or the hydric sulphide (H 2 S), is a colourless and 

 horribly-smelling gas, and arises from putrefying vegetable and animal 

 matter which contains sulphur. The odour of rotten eggs is due to this 

 gas, which is very dangerous when breathed in a pure state in drains, etc. 



liBifflll 



Fig. 385. Experiment to show the existence of gases in solution. 



It can be made by treating a sulphide with sulphuric acid. It is capable 

 of precipitating the metals when in solution, and so by its aid we can dis- 

 cover the metallic ingredient if it be present. The gas is soluble in water, 

 and makes its presencs known in certain sulphur springs. The colour 

 imparted to egg-spoons and fish-knives and forks sometimes is due to the 

 presence of metallic sulphides. The solution is called hydro-sulphuric acid. 

 PHOSPHORUS occurs in very small quantities, though in the form of 

 phosphates we are acquainted with it pretty generally, and as such it is 

 absorbed by plants, and is useful in agricultural operations. In our organi- 

 zation in the brain, the nerves, flesh, and particularly in bones phosphorus 

 is present, and likewise in all animals. Nevertheless it is highly poisonous. 

 It is usually obtained from the calcined bones of mammalia by obtaining 

 phosphoric acid by means of acting upon the bone-ash with sulphuric acid. 



