414 Intelligence and Miscellaneous Articles. 
lution of this oxide in an alkali deposits, on evaporation, crystals of 
metallic tin; according to others it yields anhydrous crystals of 
protoxide of tin. M. Fremy found that when protoxide of tin is dis- 
solved in a small proportion of alkali, and the liquor is concentrated 
under the receiver of the air-pump, the alkali at a certain period 
seizes the water of the hydrate of the protoxide, which then becomes 
insoluble in the alkali, and is precipitated in the anhydrous state. 
When, on the contrary, the hydrate of protoxide of tin is dissolved 
in an excess of alkali, and the solution is rapidly evaporated, the 
protoxide is converted into stannic acid, which remains combined with 
the alkali and tin which is precipitated. It is therefore evident that 
it is the alkali in excess which causes the variation in the decompo- 
sition. The foregoing observations show that potash in solution 
may act upon the water of hydration of an oxide, and render it anhy- 
drous; this experiment induced M. Fremy to examine the influence 
of other bodies in solution on the hydrate of protoxide of tin, and 
this examination led to the discovery of the different isomeric states 
of this protoxide. When hydrated protoxide of tin is boiled with 
a quantity of potash insufficient to dissolve it, a period arrives at 
which the precipitate, which has no appearance of crystallization, is 
suddenly converted into an infinitude of small, brilliant and perfectly 
black crytals ; these are anhydrous protoxide of tin. This oxide dif- 
fers both in colour and in its crystallization from that prepared by the 
curious process given by M. Gay-Lussac, which consists in boiling 
protochloride of tin with excess of ammonia; but these two oxides 
may be easily reduced to the same state; for if the black oxide pre- 
pared with potash be heated ina tube, when the temperature reaches 
about 390° Fahr. it undergoes a sort of decomposition, the crystals 
separate violently, increase in volume, change their form, and are 
converted into the olive oxide, perfectly similar to that prepared by 
M. Gay-Lussac’s process: solutions of some salts possess also the 
property of dehydrating the protoxide of tin. If the hydrate of prot- 
oxide of tin be boiled for a short time in a concentrated solution of 
chloride of potassium or hydrochlorate of ammonia, the oxide is de- 
hydrated. Ifa small quantity of hydrated protoxide of tin suspended 
in a very weak solution of hydrochlorate of ammonia be evaporated, 
at the moment the salt is precipitated from solution, the hydrate is 
converted into a powder of a very fine vermilion red; this is, how- 
ever, protoxide of tin in a new isomeric state. It may be readily 
converted into the olive-coloured oxide by mechanical agency ; for 
if it be rubbed with the hand, it immediately reassumes the brown 
colour, which is characteristic of the anhydrous protoxide of tin; so 
that M. Fremy observes, he has been able to obtain protoxide of tin 
on three different physical states,—black, olive and red. 
Protoxide of tin is not the only oxide which has the property of 
being dehydrated by the action of the alkalies ; when hydrated oxide 
of bismuth is boiled in an alkaline solution, a period arrives in which 
the precipitate, which was originally white, is converted into a con- 
siderable quantity of small, yellow brilliant needles, which are anhy- 
drous oxide of bismuth. 
