1825.] ill. Berzelius on Fluoric Acid. 129 



soluble in water, and crystallizes in long prisms ; but it is par- 

 tially oxidized, and decomposed dming evaporation ; and the 

 oxide thus formed precipitates in the state of a sihcate. 



Silicated Filiate of Oxidide of Chromium. — A green coloured 

 uncrystallizable transparent mass, which deliquesces to a liquid 

 when exposed to the. air. 



Silicated puate of oxide of antimony is easily soluble in water 

 containing an excess of acid. By slow evaporation it crystal- 

 lizes in prisms, which, after being dried, rapidly fall to powder. 



Silicated finale of oxidnle of mercury may be prepared by 

 digesting newly prepared and still moist oxidule in the liquid 

 acid, it is by this means converted into a pale straw yellow 

 coloured powder. The liquid, particularly when it contains an 

 excess of acid, retains a portion of the salt in solution, which it 

 deposits in small crystals when evaporated. The solution of 

 this salt has a weak metallic taste, and is copiously precipitated 

 by muriatic acid. 



Silicated faate of oxide of mercury is soluble only in an excess 

 of acid, and crystallizes by evaporation in small yellowish 

 coloured or almost colourless needles. When put into water, 

 this salt is partly converted into a yellow coloured insoluble sub- 

 salt, while the remaining portion is held in solution by the dis- 

 engaged acid. When ignited, gaseous fluate of silica is in the 

 first place expelled, and the fluate which remains undergoes 

 decomposition in the manner already described. The yellow 

 insoluble subsalt is blackened by ammonia ; but its colour is 

 again rendered lighter by the addition of water. 



Silicated fluate of oxide of silver is a very deliquescent salt, 

 which may be obtained in white granular crystals from a solu- 

 tion concentrated to the consistence of a syrup. A small quan- 

 tity of ammonia precipitates from the solution a light yellow 

 coloured subsalt, which, when added in excess, it redissolves, 

 and leaves a silicate of oxide of silver. 



Silicated Fluate of Oxide of Platinum. — A yellowish brown 

 coloured salt, veiy soluble in water. When evaporated to a 

 tenacious syrup, and in this state digested in water, it leaves a 

 brown coloured subsalt undissolved. 



Fluosilicates. — I shall hereafter discuss the different points of 

 view under which both the foregoing series of compounds, and 

 those which still remain to be described, may be regarded. At 

 present I shall merely add, that however much we may at first 

 feel disposed to do so, the silica cannot in these compounds be 

 considered to act as an acid but as a base, and consequently 

 that the name of silicate when applied to them implies an idea 

 which their nature does not authorise. The mineral kingdom, 

 however, furnishes us with examples of compounds in which a 

 fluate is actually associated v/ith a silicate, and for which there- 

 fore the appellation of fluosilicate would be sufliiciently appro- 



New Series, voj,. ix. k 



