14 Improvements in Physical Science [Jan. 
trating the effect of air in producing the crystallization of liquids. 
21 oz. of acetic acid, obtained by distilling a mixture of acetate of 
potash and bisulphate of potash, were put into a four-ounce phial 
fitted with a ground stopper. ‘This phial may be exposed to a tem- 
perature of 14° or 9°5° without freezing. But the instant the 
stopper is taken out, it congeals. Pretty brisk agitation does not 
occasion congelation. The crystallization is not impeded, though 
the phial be opened in a room of the temperature of 50°. 
(Schweigger’s Journal, xv. 231.) 
The cause of the crystallization of liquids under similar cireum- 
stances has not been completely developed. Sir Charles Blagden 
showed many years ago that it is not the air which occasions the 
change. The observations of Dr. Coxe on this subject (Annals, 
vi. 101) deserve attention. 
2. Crystallization of Lime.—M. Gay-Lussae has hit upon a 
very ingenious method of crystallizing lime. He exposes lime- 
water in an exhausted receiver of an air-pump along with concen- 
trated sulphuric acid. When the acid becomes weak, it is with- 
drawn, and new acid substituted in its place. The lime gradually 
crystallizes, and assumes the form of a six-sided prism. (Ann. de 
Chim. et Phys. i. 334.) 
Vv. ATOMIC THEORY. 
1. Atoms of Iron, Zinc, and Manganese.—Dobereiner has pub- 
lished a set of experiments on the oxides of these metals. 
(Schweigger’s Journal, xiv. 206.) The black oxide of iron is 
composed of 100 metal + 30 oxygen, and the red oxide of 100 
metal + 45 oxygen. The oxide of zinc is composed of 100 metal 
+ 22°5 oxygen. These experiments would make the weights of 
the atoms of iron and zinc— 
Paiiiiss) dh. byh Seder sien Wabag NG 3°33 or 6°66 
PRET , CPR ee nore wats ees 
I have already given the results of my experiments with these 
metals. I am disposed to consider the real weights of the atoms of 
these metals— 
WOM 8 Phe PG Pe oe Sak ro 
rine eri oie2 2k Be hare te ey 
From the experiments of Dobereiner, it appears that the black 
manganese ore of Transylvania is a sulphuret of manganese, and 
not a sulphureted oxide, as would result from the experiments of 
Klaproth and Vauquelin. He found it a compound of 100 metal 
+ 52 sulphur. This would make an atom of manganese 3°84 or 
77. The real weight is probably the same as that of iron. 
2. Axote.—Dobereiner considers azote as an elementary sub- 
stance. He thinks it capable of combining with four doses of 
oxygen in the following way :— 
