on thejluoric Compounds. 95 



If this result be calculated upon, supposing the number re- 

 presenting calcium to be 40, as I have given it in my Elements 

 of Chemical Philosophy, the number representing fluorine will 

 be 34*2, and fiuor spar must be supposed to be composed of 

 40 calcium and 34'2 fluorine. 



Twenty-two grains of fused subcarbonate of potassa decom- 

 posed by diluted liquid fluoric acid, in an experiment made with 

 great care, was found to aiford 18* 15 grains of dry fluate of 

 potassa ; and by a very careful analysis, it was found that this 

 subcarbonate contained 31 per cent, of carbonic acid: now, if 

 the remainder of the salt be supposed to be pure potassa, and 

 the calculations be made on this idea, it will appear that fluate 

 of potassa must consist of 125 -9 of potassium and 54-74 of 

 fluorine, and the number representing fluorine must be regarded 

 as 32-6. 



The 18*15 grains of fluate of potassa decomposed by sul- 

 phuric acid afforded 38*5 of acid sulphate of potash. Supposing 

 acid sulphate of potassa to consist of two proportions of sulphuric 

 acid 150, and one of potassa 90, they ought to have given 40 

 grains, and this loss is no more than might be expected in the 

 process of decomposition and evaporation. 



In some experiments that I made on the decomposition of 

 the hydrates of potassa and soda, when decomposed by fluoric 

 acid, the results indicated a number for fluorine a little lower. 

 Thus 20 grains of hydrate of potassa were converted into 19' 8 

 grains of fluate of potassa, and 20 grains of hydrate of soda into 

 19-6 of fluate of soda: but I do not place so much confidence 

 in tiiese results, as there always was great heat produced during 

 the action of the acid upon the hvdrates ; and probably a minute 

 quantity of the hydrat-s might have been dissipated at the be- 

 ginning of the process. 



It appears reasonable to conclude, a" I have stated in my last 

 pajier, published in t!ie Philosophical Transactions, that the 

 number representing fluorine is less than half of that represent- 

 ing chlorine, about 33. 



I endeavoured to ascertain the composition of fluate of am- 

 monia, by adding together hydro -ttuoiic acid and solution of 

 ammonia of known composition ; and I found in tliis way, that 

 100 parts of solution of ammonia of specific gravity 9162 re- 

 quired for its saturation 52 grains of diluted fluoric acid of such 

 a strength, that an equal portion produced exactly 32 grains of 

 fluate of potassa. According to this experiment, fluate of am- 

 monia must consist of 9*7 of fluorine to 22 of ammonia*^'; and 

 if it be conceived that liquid fluoric acid consists of two pro- 



• Sec Elcinciitj of Cliomical I'iiilosopliy, page 2C8. 



portions 



