184 FACTS AND OBSERVATIONS. 
would prove sufficient to arrest the spread of the disease if 
they were actively enforced, but unfortunately there are many 
difficulties in the way of carrying them into effect. 
Eacts and Observations. 
The Singeing of Army Horses. —An order has been 
issued from the Horse Guards to the effect that horses are 
not to be singed to an extent to render blankets necessary as 
a protection from the weather, and under no circumstances is 
clipping to be permitted. 
Inefficacy of Immature Cantharides. —Recent in¬ 
vestigation shows that young cantharides do not possess the 
epispastic property, and it would seem that in medium-sized 
insects it is equally wanting. It is only the full-grown in¬ 
sects that will raise blisters. Cantharadine appears not to 
be developed until the complete maturity of the insect. In 
purchasing cantharides, therefore, those only should be 
chosen which have attained their full growth.— Pharm. Journ . 
Adulteration of Catechu. —It is a well-known fact, 
that catechu is often adulterated; the sophisticated substance 
injuriously affecting various operations in which it is em¬ 
ployed, especially dyeing and calico-printing. According to 
Tissandier, genuine catechu, when exhausted by means of 
ether, loses 53 per cent, of weight, leaving, after drying, 47 
per cent, of residue. A mixture of catechu and alum gives a 
white precipitate withjnitric acid and with chloride of barium. 
— Ibid. 
Preparation of Hydrogen Gas. —It is stated that 
MM. Tessie du Motay and Marechal have lately discovered 
a new and economical method of producing hydrogen gas. 
The process consists in heating the hydrates of the alkalies 
and alkaline earths with coke, coal, charcoal, &c., to a red heat, 
whereupon carbonic acid and hydrogen are given off abun¬ 
dantly; and as the decomposed hydrates, especially that of 
lime, can be used indefinitely, by simply remoistening them 
with water, the method is very economical. In this opera¬ 
tion the hydrogen gas is generated without any special pro¬ 
duction of steam, and may thus be produced without any 
other generating apparatus than the retorts themselves; and 
as these retorts are not exposed to the direct action of the 
steam, they are not subject to any interior deterioration. This 
