Periscope of Medical and General Science in their Relations to Dentistry. [Volume: 2, Issue: 11, June, 1861, pp. 625-637]

636

THE DENTAL COSMOS.

was such as to permit the separation of the gold contained in each kind
of coin. A distinct button of metallic gold was obtained in every
instance before the blowpipe, but the amount of gold varied to a considerable extent; it was abundant in the American and Spanish coin, less
was observed in the English and Mexican, and but little in the French
coin or in the American fine silver. Briiel has remarked 'that the process of separating lead and silver was less perfectly executed in the ages
of antiquity than is at present the case,' (Karsten u. Dichens Archiv
fir Mineralogie, etc., 1844, xviii., 509;) yet in none of the recorded
analyses of ancient silver coins has any one detected so large an amount
of lead as the authors have shown to occur in American fine silver of the
year 1860, if a single analysis of Professor Draper's be excepted, which
gave nearly three per cent. of lead in a silver coin of Hadrian. It is
probable, however, that the methods of analysis (none of which are recorded) employed for separating lead from silver by other chemists were
less delicate than those which the authors made use of and have fully
described. The occurrence of lead in the American silver coin could
probably be mainly, if not altogether avoided, by employing zinc free
from lead, such as is produced at the zinc works of Bethlehem, Pennsylvania. It is noteworthy that the American system of amalgamation,
which has been so frequently criticised by European metallurgists, affords
silver which is less strongly contaminated with lead, and is probably
purer in other respects, than is produced by any other process of manufacture.-Proceedings of the American Academy, V., 52, Cambridge,
September, 1860." —(American Journal of Science and Arts.)
Infant Feeding and its Influence on Life, or the Causes and Prevention of Infant Mortality.-In the course of a complimentary notice
of an English work on this subject by Dr. C. H. F. ROUTH, the Med.
Critic and Psychological Journ. gives the following interesting extract
therefrom: "The whole analogy of comparative anatomy proves that all
young animals require animal food for some time after birth, because this,
or some adventitious animal structure, is generally supplied by the parent.
The infant itself is so anatomically and physiologically made as to be
capable of digesting animal food only.
" In many species of mollusca, and especially in gasteropoda, in many
insects, and among the batrachian reptiles, the mother produces, together
with the egg, what is called a nidamentum, which nourishes it for some
time after its birth. Certain insects even feed upon the external envelopes
which surround them, as in the case of the stratismys chameleon.
" The yellow substance which surrounds the abdominal parietes in some
animals, or which is inclosed in the central abdominal cavity, is an auxiliary of this kind. Its presence explains the fact that spiders and snakes,
for instance, remain some time after birth without requiring any other
kind of food. The raw food which the greater number of birds give to
their young is exclusively animal; hence the more readily obtainable and
digestible. The northern ducks and the petrels, with their nests situated
on high rocks near the sea, easily procure this food, and they always return
to their nests richly laden with fish. The sparrows nourish their young
with insects and worms, which they find everywhere in abundance; and
hence certain rapacious birds, which require a greater amount of animal
food for their young, become at the breeding season particularly audacious
in order to procure it.