Hydrous Basic Phosphate of Alumina. 155 



Before the blowpipe it swells, cracks open, rounds and turns 

 white, giving a sodium flame. Yields water in the closed tube ; 

 gives hydrogen phosphide with the magnesium test ; turns 

 blue with cobalt nitrate. With borax in O. F. gives a clear 

 bead ; yellow, hot ; colorless when cold, with perhaps a tinge of 

 green if highly charged; opaque by flaming if saturated. 

 When ignited it sinters. Partly decomposed by acids. Finely 

 powdered and strongly heated with con. HCl or HNO3 

 about 20 per cent, remained undissolved. This residue on 

 ignition was pure white and entirely dissolved on further 

 treatment with acid. But if the mineral was first ignited and 

 then heated with acids, about 11 per cent, remained undis- 

 solved. This residue, on ignition, was white with a pinkish 

 tinge and resisted further action of acids. 



In course of this investigation analyses of variscite were 

 made which closely agreed with those given by Mr. Packard. 

 They did not, however, confirm the statement that, before 

 ignition, variscite is insoluble in acids. When finely powdered 

 and strongly heated for some time, it completely dissolved in 

 either HCl.HJSTOa. or H^SO^ — perhaps most easily in the last. 

 Heated in fine powder for 40 hours to 100-130 C. variscite 

 gave off 22'22 per cent, water, then over the blast-lamp for 30 

 minutes lost 0*50 more. 



One interesting specimen shows the green variscite with its 

 lower surface changed to a yellow alteration-product. On 

 top, and seemingly running into the green, is a colorless radi- 

 ate rosette, strongly resembling wavellite, but with rather 

 stouter prisms. Imbedded in this rosette is a concentric mass 

 of wardite, differing in form and color from both the varis- 

 cite and the radiate mineral. Attached to another piece of 

 superficially altered variscite was a nodule of the size and 

 shape of a pea, itself covered with the same alteration prod- 

 uct. Detached, it was found concentric in structure, having 

 both white and colorless layers and hard enough to defy the 

 point of a knife. It looked like chalcedony, but the alteration 

 zone showed that it probably was amphithalite. 



Am. Joue. Sci. — Fourth Series, Vol. II, No. 8. — August, 1896. 

 11 



