OCCURRENCE OF EVANSITE IN TASMANIA. 383 
The phosphoric acid determined by molybdate of ammonia gave 
17:996 percent. By citric acid and precipitating with sulphate of 
magnesia 18-232 per cent., mean 18-114 per cent. The amount 
of water present was 41-266 per cent., the greatest precaution 
being taken to prevent loss by decrepitation. The loss equalled 
-434 per cent., this may be considered principally as alkalis; all 
attempts to detect ammonia, as indicated by the alkaline water, 
failed. On evaporating the filtrate from which the phosphoric 
acid and the alumina had been removed, the minute quantity left 
gave a strong sodium flame. The white opaque cellular portions 
of the specimen are very siliceous. The rock appears to be a slaty 
one, and a few particles of galena are present. 
The formula Al,P,O,,+18H,O gives 
Theoretically :—Alumina ... 39°87, Found:—40:186%. 
ty Phosphoric acid 18°35, i 181147. 
% Water... eee eae $ 41-2667. 
loss °4347. 
100-00 
100-000 
Since the above paper was read, my attention has been directed 
to a ‘Catalogue of the Minerals of Tasmania” by Mr. W. F. 
Petterd, published during the present year. On page 27, under 
Evansite from Zeehan is the following :—“ A rare species, occurr- 
ing as botryoidal incrustations which are often almost colourless 
but sometimes milky-white, at all times having an attractive 
pearly lustre. It appears to differ from the typical form in having 
a proportion of silica chemically combined. ‘The examples were 
obtained in a silver-lead lode, with galena and sphalerite.” 
From a courteous communication since received from Mr. 
Petterd, it appears that the above is all the information published 
in regard to the Tasmanian mineral, so that my analysis and 
observations will prove acceptable. 
