Physics and Chemistry. 111 
On the preparation of barium chlorate-—Branvavu has pro 
posed the following simple method for the preparation of se 
chlorate: Commercial crystallized aluminum sulphate, sulphuric 
acid, and i chlorite, in the ratio of one molecule of each of 
the two former to two of the la atter, are ac with water to the 
consistence of a thin wee warmed for half an hour on the water- 
bath, allowed to cool completely, and paras with alcohol in excess, 
Upon filtering, and neutralizing with barium hydrate, barium sul- 
phate and some aluminum y drate are precipitated, and barium 
chlorate remains Lanes The alcohol is distilled off, and the 
filtrate on evaporation yields crystals of the pure barium chlorate. 
The only precan an necessary is to have the aluminum sulphate 
and the menpharin acid in slight excess. wa Fo Ch. minis my igs 
Sept. 1869 
properties of Selenitum.—Ratukk has Rl ey in 
the Halle devon the various modifications which selenium, 
like sulphur, is capable of gcc Notwithstanding the differ- 
ence in the behavior of the various forms of each, respectively, 
to solv ents, especially €S,, Rathke places the sh black se- 
lenium with the rhombic variety of sulphur, and the red amor- 
phous ‘deta with the insoluble oe form of sulphur. As 
in eo cease of sulphur, the latter variet selenium is produce 
b ecomposition of selendithionates i See set selenium in 
ediclties sulphites) by acids; by the action of os n selenium 
chlorid; and by _ sudden cooling of fused se lela " So on ela 
sien distinct er ryetals of black selenium are pro roda ced, rect y 
as W y the similar decomposition of alkaline sulphids, large 
aealtie crystals of sulphur separate. ough red selenium is 
more stable than the corresponding form of sulphur, yet, like this, 
it passes into the other variety on raising the temperature to 100° 
C., with a distinct evolution of heat. The specific gravity of selen- 
ium in these forms, is as follows: For the black variety, 4°80 to 
er chlorid saturated with igi ale the aid of heat, de- 
posits on = erystals of sulphur, leaving selenium chlorid, in 
which selenium dis ft 
from which, on standing, the a variety of selenium separate 
ie , but 
obtained by ac ctin sie selenium be id with moist vapor of car- 
could not be paaeed yee rachlorid itself, does not dis- 
solve the black variety of oe eencia dissolves both, 
