32 | : it 4 
Jem ava eA ee eee, 2 Jee Sa gages: <2 ee She seas Sos elle. 13 per cent. 
Woody fiber, &¢...-. 2... 2-2-2. 2-2 + eee eens eee eee eee eee eee eee eee 87 per cent. 
100 per cent. 
It will be seen that this, when compared with other tanning mate- 
rials, is certainly a very valuable product. According to E. Wolff dif- 
ferent oak-barks, of trees from five to fifty years old, yield from 10.86 
to 15.83 per cent. of tannin, the lower results having been obtained 
from an examination of the crude bark of old trees, while the higher 
results were obtained from examination of the inner bark of young 
trees. Biichner, in his researches in 1867, determined that the best 
kinds of oak-bark contained but 6 to 7 per cent. of tannic acid. The 
bark of the hemlock, (Abies canadensis,) so much used throughout the 
United States, contains, according to J. Feser, from 5 to 15 per cent. 
of tannin, while Dr. Wagner finds but 7.3 per cent. It will be seen 
that the amount of tannin contained in the mesquite-wood is higher 
than that of many other tanning materials, and thus when compared 
with them this product is as valuable as any other material used in this 
branch of industry. 
USE OF SULPHUROUS ACID IN MANUFACTURE OF ALCOHOL.—The in- 
creased yield of alcohol, obtainable from different kinds of grain, by the 
use of- sulphurous acid, has led to its very general use in many parts 
of Europe. From the investigations of Hemilian and Melnikoff it would 
seem that the weak solution of sulphurous acid used dissolves the gIn- 
ten and other albuminoid substances, thus allowing the starch to come 
into more perfect contact with the solution of diastase. It has, there- 
fore, two different actions, the one being the partial destruction of the 
fermenting power of the diastase, while the other promotes the inversion 
of the starch. It was determined that the largest quantity of glucose 
is obtained when the cold maceration is continued five or six hours 
with a solution containing an amount of sulphurous acid equal to 0.1 to 
0.13 per cent., the quantity of malt and meal used. If, however, the 
maceration be continued for eighteen hours, with cold water alone, the 
effect is the same as when the sulphurous acid is used, except that we 
have acidification and incipient putrefaction. The use of sulphurous 
acid in the most favorable conditions is found to increase the yield of 
glucose from 2 to 3 per cent. of the weight of the grain employed. The 
method of using it, as suggested by Hemilian and Melnikoff, is as fol- 
lows: The meal only, without the malt, is macerated in the cold with 
the solution of sulphurous acid, of the strength above mentioned, and 
then heated to 50° C., so as to volatilize any free sulphurous acid. The 
malt is then added, and the mixtare, being all the time well stirred, is 
heated from 70° to 75°, these temperatures being best suited to the 
saccharification. The principal utility of sulphurous acid is due to 
its power to prevent the formation of free acids, which are always gen- 
erated at the expense of the alcohol, while the decrease of free acids in 
the spent wash renders it more valuable as food for cattle, since its nutzri- 
tive value is thus increased and it is less injurious to health. 
SULPHUROUS OXIDE ON VEGETATION.—It has been observed that trees 
in the neighborhood of smelting-works are injured by the fumes of sul- 
phurous oxide proceeding from them, and that the Conifere suiter 
greater injury than ordinary foliaged trees. The fumes are absorbed 
through leaves entirely, not by the stomata alone, but by the whole 
surface of the leaves. It could have no influence upon the plants 
_ through the soil, since the sulphurous oxide would be oxidized and sul- 
