508 Scientific Intelligence. 
SCIENTIFIC INTELLIGENCE. 
I. CHEMISTRY AND PHysICcs. 
1. On the decomposition of Potassium chlorute by heat.—At 
the suggestion of Thorpe, FrRanKLAND (P. F.) and Dryewaty 
have studied the decomposition which potassium chlorate under- 
goes when heated, extending their observations also to the per- 
chlorate. In the first series of experiments, the chlorate was 
heated over a naked flame, different quantities of oxygen being 
driven off in each experiment and determined by loss of weight. 
The chloride formed, as well as the chlorate remaining, were 
also determined. In the first two experiments, 2°66 and 5°19 
per cent of oxygen (calculated on the weight of KCIO, taken) 
were evolved respectively. And the decomposition proceeded 
according to the equation (KCI1O,),=(KCIO,).+ (KCl),+ (0,).. 
In the third, in which 6°47 per cent of oxygen was evolved, the 
reaction was intermediate in its results between the above equation 
and (KC10,),,=(KCI1O,),+(KCl),+(O,),. Since there was no guar- 
antee in these experiments that the reaction was not complicated 
by the decomposition of the perchlorate at first formed, the authors 
made a second series of experiments, selecting as the temperature 
that of boiling sulphur, since at this temperature the perchlorate is 
not decomposed. The decomposition was at first active, but soon 
became sluggish. In one experiment 5°3345 grams of chlorate 
exposed in the sulphur bath for 98 hours, lost 116°6 milligrams 
during the first five hours, and only 8 milligrams during the last. 
In the first two experiments, in which 6°89 and 6°78 per cent of 
oxygen were respectively evolved, the reaction took place nearly 
in accordance with the: second of the above reactions. In the 
third experiment, powdered glass was mixed with the chlorate ; 
and then the decomposition was almost complete, 14°3 per cent 
of oxygen being evolved, nearly according to the formula 
(KC1O,),=KCIO,+KCI+0,. Hence the decomposition of potas- 
sium chlorate by heat more nearly approaches the equation 
(KCIO,),=KCIO,+KCI-+O, in proportion as this decomposition 
is more complete. In experimenting with perchlorate, definite 
portions were heated over a naked flame in a piece of combustion 
tube sealed at one end and loosely plugged with glass-wool at 
the other, a different proportion of oxygen being liberated in 
each experiment. In the residue the proportion of chloride to 
chlorate was determined. The results when tabulated form a 
continuous series; the proportion of chlorate formed diminishes 
as the oxygen evolved increases, while the chloride produced 
increases. When the oxygen set free was 8°77 per cent, the chlo- 
rate formed was 24°85 per cent of the perchlorate employed; but 
when 36°81 per cent of oxygen was evolved, the chlorate was 
only 5°27 per cent. Heating the perchlorate in sulphur vapor, 
when previously mixed with MnO,, resulted in a complete decom- 
