1819.J On the Chemical Constitution of Acids, &c. 281 



I consider it as nearly superfluous to say any thing about the 

 place which lasionite should occupy in the mineral system ; 

 as this presents itself almost spontaneously ; and every minera- 

 logist will be able, without difficulty, to give it the place to which 

 it belongs in the system that he has adopted. Lasionite must 

 be ranked among the salts, and when these are divided into 

 genera, according to the acids which they contain, which, in 

 my opinion, is the best and most convenient method, it will 

 come as a phosphate, and be placed immediately after apatite. 



Lasionite may be formed artificially by various methods ; but 

 it can be exhibited only in a pulverulent form, like the earthy 

 wavellite when it occurs in that state.* We obtain it when we 

 dissolve fresh precipitated alumina in phosphoric acid, and 

 precipitate by means of ammonia ; probably likewise when we 

 decompose an aluminous salt, as alum, by means of phosphoric 

 acid, or a phosphate soluble in water, in the usual way, and then 

 pour ammonia into the liquid. When we mix together a solu- 

 tion of alum and phosphate of ammonia, a slight muddiness 

 occurs at first, which speedily disappears. From this mixture, 

 phosphate of alumina may be precipitated by acetate of ammonia, 

 even when an excess of acetic acid is present. This mode of 

 proceeding is probably the best, because even when an excess 

 of alum is present, it will not occasion the precipitation of any 

 uncombined alumina. The analysis of artificial lasionite gave a 

 result very nearly the same with that of the natural mineral ; only 

 the loss of weight in the fire was considerably greater, although 

 i thad been well dried before it was exposed to a red heat. 



Article IX. 



Observations on the Relation of the Law of Definite Proportions 

 in Chemical Combination, to the Constitution of the Acids> 

 Alkalies, and Earths. By John Murray, M.D. &c. &c. Read 

 before the Royal Society of Edinburgh, March 2, and May 

 18, 1818. (Not yet published.) 



The law that every body enters into chemical combination in 

 a certain equivalent weight to others, and that when it combines 

 in different proportions with another, these proportions have a 

 simple arithmetical ratio, is perhaps the most important that has 

 hitherto been discovered in the science of chemistry. It is now 

 so far established, notwithstanding some difficulties which attend 

 it, that when a view of the constitution of an extensive series of 



• The so called earthy talc, from Freiberg, which IF. John analyzed (Schweig- 

 ger's Journal, v. 222), may, perhaps, belong to ii ; but I can determine nothing on 

 that point, as I am not possessed of the mineral. 



