Johnson—The Chemistry of Boron. 
531 
sition occurs, even in several days. But if the water is heated 
action soon sets in and continues quite rapidly giving aniline 
and boric acid. 
Pyridine and B Br 3 form a white, amphorous precipitate in 
C Ci 4 as medium. It is surprisingly stable in water, not de¬ 
composing; readily unless boiled for some time. It analyses up 
to B BrJ W. 
The methods of analysis relied upon in the foregoing work 
consisted in determining the bromine gravimetrically as silver 
bromide, and the nitrogen by the Kjeldahl procedure. The 
combustion method will be worked later but thus far the Kjel¬ 
dahl method has given sufficiently satisfactory results. 
Another phase of boron chemistry which presents interesting 
aspects is the action of born halides on the unsaturated hydro¬ 
carbons. |The olefine and acetylene series. As an example: 
Dilute solutions of amylene and B Br 3 in C Cl 4 as a medium 
were brought together slowly, the system being cooled with ice- 
water, and to my surprise, pure, amorphous boron was precipi¬ 
tated in an extremely attenuated, colloidal condition. The 
boron will, in fact, remain suspended in the reaction mixture 
an indefinite time. That the material was pure boron, was 
proved beyond a doubt by evaporating off all the volatile prod¬ 
ucts and washing the residue with carbon tetrachloride and 
then with ether. As a film it was of a maroon color, very 
stable in air, even when heated to about 500°. When heated 
in a glass tube with pure oxygen it was burned to white boric 
oxide. The gas drawn from the tube and then through lime- 
water gave no test for carbon dioxide. 
The reaction of B Br 3 and the unsaturated compounds is 
doubtless very complicated, however, and very exact conditions 
must be maintained to obtain certain definite end-products. If 
B Br 3 and amylene are brought together directly they react 
with explosive violence and there is charring of the organic 
substance, and most irritating fumes evolved. As the other ex¬ 
treme, the passage of B Br 3 fumes carried by a current of hy¬ 
drogen into amylene dissolved to the extent of 10 to 20 per 
cent in carbon tetrachloride and the whole reacting mass cooled 
