500 Screntific Intelligence. 
nitrogen, which combines with boron at high temperatures, form- 
ing the nitride. The pure amorphous boron is a powder of a 
light chestnut color having a density of 2°45. Its electrical con- 
ductivity is very weak, and it does not fuse at the temperature 
furnished by the electric arc. This observation on the infusibility 
of boron places this element beside carbon as an infusible sub- 
stance, whereas previous observations, made with impure material, 
had indicated that it fused in the electric arc. The substance 
combines more readily with non-metals than with metals. Sodium 
and potassium can be distilled in contact with it without action, 
It burns in the air and especially in oxygen with great brilliancy. 
and it combines with sulphur with incandescence. It has an 
especially great affinity for oxygen, forming an explosive mix- 
ture with lead peroxide, and producing an active gun-powder 
when mixed, in place of charcoal, with sulphur and potassium 
nitrate. It reduces sodium carbonate with incandescence at a 
low red heat, potassium carbonate is reduced at a higher tempera- 
ture, while calcium and barium carbonates are not reduced. It 
has a greater affinity for oxygen than have carbon and silicon, for 
it reduces the oxides of these elements at high temperatures. The 
powder reduces cold potassium permanganate and ferric solutions, 
and, by warming, it precipitates silver in a crystalline condition 
from silver nitrate solutions.—Ann. Chim. Phys., VII, iv, Oct., 
1895. H. L. W. 
4. The preparation of Tin Tetrachloride and Tetrabromide.— 
The handbooks of chemistry recommend the preparation of these 
substances by the action of the halogens upon molten tin, but 
Lorenz finds that no artificial heating is necessary, and in fact, 
that the action is most favorable near the ordinary temperature. 
For the preparation of tin tetrabromide the author places solid 
pieces of tin in a distilling-flask and allows liquid bromine to 
drop upon them from a capillary opening at the end of a separa- 
tory funnel. The addition of the bromine is so regulated that the 
temperature of the flask is kept between 35° and 59°C. The 
liquid tetrabromide collects at the bottom of the flask. The 
product is finally distilled from the same flask in the presence of 
some remaining metallic tin, giving a perfectly pure, white 
product. For the production of the tetrachloride in large quan- 
tity a glass tube closed at the bottom, like a large test-tube, 30 
or 40 inches long and 2 or 24 inches wide, is provided with a 
stopper having two holes, through one of which a chlorine deliv- 
ery tube extends to near the bottom of the large tube. Through 
the other hole, for a short distance, extends the end of an upright 
condenser for preventing the loss of the product towards the end 
of the operation. The large tube is nearly filled with granulated 
tin, and chlorine is passed in through the delivery-tube. It is best 
to have a little previously prepared tin tetrachloride in the bottom 
of the apparatus so that the delivery-tube dips under this liquid. 
Chlorine is now passed in at the ordinary temperature. Its dis- 
appearance is extraordinarily prompt, and the speed with which 
