Hussakitc. — Kraus and Reitingcr. 47 
nor do any of the analyses of xenotime, which were at our 
disposal, «how its presence. 
Chemical Analysis. 
The first point to be settled by the quantitative analysis was 
whether the sulphates form an accessory or an essential con- 
stituent of the mineral. The latter was found to be the case. 
The following" statement concernino^ the method of the quanti- 
tative chemical analysis may prove to be of interest to miner- 
alogists. 
The mineral is a sulpho-phosphate, and aside from those 
two acids, contains only the earths of the yttrium group. 
FcoO. was found to be present in very small quantities, while 
Al^Oo, CaO, and MgO could not be determined. The" de- 
composition was effected by means of the alkali carbonates. 
The operation takes place quite easily. The material usually 
requires to be heated for half an hour before the blast-lamp. 
The fused mass was first treated with water. The earth car- 
bonates are insoluble ; but on the other hand, all the 
sulphuric acid and most of the phosphoric acid are dis- 
solved. In this aqueous solution the amount of the two acids 
could then be determined. The portion, insoluble in water, 
may be treated in two ways. First, it may be dissolved in 
nitric acid and the small quantity of phosphoric acid precipi- 
tated by means of molybdenum solution. After the removal of 
the molybdenum solution and the precipitation of Fe.Oo and 
AloOa with sodium acetate, the earths may be rendered insolu- 
ble by the addition of ammonia. Or, second, it may be dissolved 
in hydrochloric acid, and after precipitation of the earths 
as oxalates, the phosphoric acid, Fe^O;,, and ALOg may be de- 
termined as usual. By means of continued heating before the 
blast-lamp, the earths were converted into the oxides. After 
treating them with sulphuric acid, the equivalent weight was 
determined in the usual way. In this manxier the atomic 
weight of the mixture of rare earths was found to be, in this 
case, 103.25. The cathode-luminescence method* was used 
to spectroscopically show the presence of a small percentage 
of GdjOg together with considerable YoOg. The EroOg, con- 
tained in the mixture of earths, was determined spectroscopic- 
*Muthttiann und Baur, Ber. d. d. chetn. Ges. 3.9, 1748. 
