THE ACIDS 



1 7 



system was devised in which each salt was named after the 

 acid and the BASE (metal, alkali, or earth) from which it was 

 derived, e.g., nitrate of silver, sulphate of potash, muriate of 

 lime. This system was initiated about the middle of the 

 eighteenth century and completed by a group of French 

 chemists in 1787*; it led inevitably to the inclusion in the 

 category of " salts " of many insoluble and tasteless sub- 

 stances. Selenite, for instance, when prepared by the action 

 of oil of vitriol on lime or chalk, could scarcely be excluded 

 from the category of salts merely because it was only slightly 

 soluble in water ; for the same reason it was necessary to 

 regard as a salt the 

 insoluble muriate of 

 silver, which could 

 scarcely be separated 

 in an arbitrary way 

 from the soluble muri- 

 ates of copper and gold. 



Some of the more 

 important salts pre- 

 pared with the help of 

 the acids are described 

 below. 



Vitriols or sulphates. The salts prepared by the action 

 of oil of vitriol on metals were of a glassy crystalline 

 character, which won for them the name of VITRIOLS. 



"Out of all Metals there can be made a Vitriol or 

 Chrystal (Chrystal and Vitriol is taken for one)." (Basil 

 Valentine, Last' Will and Testament, p. 157.) 



This name was afterwards limited to crystals prepared 

 from, or related to, oil of vitriol. The most important of 

 these were GREEN VITRIOL, and BLUE VITRIOL (Fig. 9), 



1 The Methode de Nomenclature Chimique, by MM. de Morveau, 

 Lavoisier, Berthollet, and Fourcroy, was published in Paris in 1787, 

 and translated into English in 1788 and 1796. 



FIG. 9 CRYSTAL OF BLUE VITRIOL 

 OR SULPHATE OF COPPER. 



