280 Prof- Fuclis on Lasionite and Wave/lile. [Oct, 



which was mixed with the phosphate of lime, and made the 

 quantity of phosphoric acid be stated a little above the truth. 

 In other respects, this result agrees very well with the preceding, 

 and with that which the lasionite gave. We are entitled 

 from it to conclude, that wavellite is not a hydrate, but a phos- 

 phate of alumina, and constitutes only one genus along with 

 lasionite, which I propose to distinguish by the euphonious word 

 lasionite. I examined a portion of this mineral for fluoric acid, 

 but could discover no trace of it. 



In my former notice, I stated a conjecture that phosphoric 

 acid may constitute an ingredient of many minerals, and when 

 it is in combination with alumina, it may be easily overlooked by 

 chemists ; because phosphate of alumina and pure alumina have 

 the same solvents and the same precipitants, and alum may be 

 formed from the one as well as the other. I have now more 

 reason to repeat this conjecture, seeing that the presence of 

 phosphoric acid has been overlooked in wavellite, though it 

 exists in that mineral in such considerable quantity. The chief 

 reason of this oversight was, that the alumina which it contained 

 formed alum with sulphuric acid and potash. The formation of 

 alum then is no sure indication of the purity of alumina, and 

 shows only that alumina is present. If phosphoric acid be in 

 combination with it, this acid may be either separated by the 

 sulphuric, or it may enter as an ingredient along with it into 

 the alum ; a point which can only be determined by an experi- 

 mental investigation. Its presence in the alumina betrays itself, 

 as has been already remarked above, when the mineral is sub- 

 jected to the action of the blow-pipe by the bluish-green colour 

 which it gives to the flame. This happens even when the 

 proportion of phosphoric acid is very small.* The examination 

 of alumina, therefore, for phosphoric acid is easy, and no 

 analyst will overlook it hereafter. But this is not sufficient. 

 According to the common method of separating silica, phosphate 

 of alumina may easily be confounded with it. Hence it will be 

 necessary to apply the same test to the silica. And as the 

 alumina may conceal other substances as well as phosphoric 

 acid, it will be necessary, by analytical trials, to correct our 

 notions of the characters of this earth. Above all, the analysis 

 of sapphire and corundum ought to be repeated, as it is not 

 improbable that these minerals, together with alumina, may 

 contain some other substance ; perhaps a metallic oxide. 

 Probably one or other of the new earths might, by a more 

 accurate analysis, be divided into alumina and some other sub- 

 stance. 



» The compounds of phosphoric acid which, like apatite, do not coloar the 

 flame of the blow-pipe, acquire that property if they he plunged into sulphuric 

 acid. This, therefore, is a very good method of knowing the presenceof phosphoric 

 acid. It may be employed likewise for the compounds of boracic acid, which, 

 give the flame a much finer, livelier, and purer green colour than phosphoric acid. 



