IS 1 4.] On the Cause of Chemical Proportions. 55 



experiments, either with phosphorous acid, or with the white or red 

 oxides of phosphorus ; but 1 should be disposed to consider the 

 white oxide as P + O, phosphorous acid as P + 2 O, and phos- 

 phoric acid as P -r 4 O. The nature of the red oxide is still 

 doubtful, in consequence of the opposite conclusions drawn by 

 Thenard on the one hand, and Vogel and Seeback on the other, 

 from their experiments. 



4. Fluoriciim, Jiuoric radicle (F). — The volume of fluoric radicle 

 might be calculated in the same way as that of the muriatic, if we 

 had exact analyses of a sufficient number of fluates. Different 

 chemists have analysed native fluate of lime, and have obtained re- 

 sults too variable to put any confidence in them. Wenzcl found it 

 a compound of fluate of lime and fluate of alumina. According to 

 him, 100 parts of fluoric acid neutralize 202 parts of lime, 

 llichter found that 100 parts of fluate of lime produce 147'3 parts 

 of sulphate of lime. Thomson obtained 156-6 parts of sulphate of 

 lime, and Klaproth extracted 123J- parts of carbonate of lime. If 

 we calculate the quantity of lime contained in the sulphate and 

 carbonate, we obtain the proportion which exists in the fluate. Mr. 

 Dalton, in an analysis of which I do not know the details, finds 

 still less lime in this fluate than the other chemists. According to 

 these experiments, 100 parts of fluoric acid ought to combine with 

 200 parts of lime according to Wenzel, with 160 according to 

 Richter, with 191-58 according to Thomson, with 228 according 

 to Klaproth, and with 150 according to Dalton. These differences 

 announce that the fluate of lime is not always of the same nature. 

 It probal)ly always contains a portion of triple fluate of lime-and- 

 silica, which occasions this great diversity in the analytical results. 

 To discover the capacity of saturation of fluoric acid, it is necessary 

 to examine an artificial combination absolutely pure : for examjjle, 

 fluate of barytes and fluate of silver. Mr. John Davy has examined 

 the gaseous fluate of silica; and if the composition of silica were 

 known as exactly as that of lime, it would be easy to determine th« 

 constitution of the acid from that analysis. When I come to speak 

 of silica, I shall have occasion to state more at large the composi- 

 tion of that earth. 



All these experiments show that fluoric acid neutralizes such a 

 quantity of base that the acid can only contain a quantity of oxygen 

 equal to that which exists in the base. If we take the analysis of 

 fluate of lime by 'i'homson as the base of our calculation, the acid 

 ought to contain about 55 per cent, of oxygen ; but if we employ 

 the analysis of siliealed fluoric acid made by Mr. John Davy, the 

 acid ought to contain from 7^' to 77'^ pt^i" cent, of oxygen. In 

 order to determine how many volumes these 77 P^'r cent, amount 

 to, we may employ an experiment of Gay-Lussac, confirmed by 

 Mr. John Davy, according to which I volume of silieated fluoric acid 

 condenses 2 volumes of ammoniacal gas. The fluoric acid and silica, 

 from what has just been said, ought to contain equal volumes of 

 oxygen; but ammonia contain-i the fourth pait of its volume of 



