New-York tribune. [volume] (New York [N.Y.]) 1866-1924, 1875-04-13
APPLIED SCIENCE. ,

THE HARDENING OF PLASTER OF PARIs.-Landrin
distinguished three phases in tho hardening of gypsum
by watching its progress under the microscope: ~
the ASSUMPTION of crystalline condition by the calcned
plaster in contact with water; (2 the solution of
certain portion Of the crystal by the surrounding
water; (3) the evaporation of certain amount of
water by reason of the heat generated in taking up
the water of capitalization and the formation of
crystal, which affects the capitalization of the
whole mass just as a crystal in supersaturated sOlu-
ton of salt. During the first two phases no harden
ing takes place, and is only after some time that the
maximum degree of hardness Is reached, and the
amount of water then present is only double that IN
the ordinary hydrate or gypsum. definite mixture
of water and plaster. witch hardened IN ten minutes
was found to lose water gradually for Is days, until
the above composition was reached, when there was
no further loss of water.
IvTRAvENoUs USE OF CHLoRAL FOR AS4sTHEsIA.-
Ore, in article upon tho employment of an ntra-
venous introduction of choral in anBsthesa,
marks that an essential condition consists in the
pnncture of the vein without laying it bare. For
use one part of choral is dissolved in three of
water; sometimes however, one part to five Five
grammes of the chlOral itself in this mixture
necessary to produce satisfactory anpsthesia, and
oven more i'm some cases. Where tho dose necessary
for anBsthesa is from five to eight grammes, these
should be introduced at the ratio OF about one
grammc per minute, TO allow its thorough cir
culation throughout the system. The advantages of
this method of anRshesa that the respiration is
never disturbed and perfect insenslbllty can be Ne
cured for a period of time varying with the dose;
no undue excablity is produced, and there Is never
any vomiting, while the operation is always fol-
lowed by calm, regular slumbcr, which may bc made
to last H. Is, ~ hours, as frequently to
do away completely with the common effects of Sc
operations. Finally, there are never any symp-
toms of phlebets or hernaturia when the operation
liz properly performed.
FISH CONSUMPTION or WASHINGTON IN 1874
The report of Mr.. c. Ludington, Food Inspector to
the Board of Health of the City of Washington
gives a very interesting account OF the consumption
of animal food in great city, and it is much to be
desired that similar statistics be supplied for such
points az New-Yorl, Boston, Philadelphia, Balti-
more Cincinnati, Chicago, st. Louis, &c In respect
to Gsh" it appears that for the market of Washing
ton alone during II months from Sept. 80, 1873, to
Sept 80, 1874, the following numbers were in
spected:
slad .,.......... 82s,837 sturgeon. ........ 9l9
Terin2 G,5G7,2io bushels Of oysters 5e G9 az
tiIors. sO,s41 Number Of 297,25O
Bunches fish,. 667,291
The fish weighed, in the aggregate. about H.
O0O 900 pounds; by far the greater proportion being
derived from the Potomac River and the lower part
of Chesapeake Bay. And when we bear in mind the
other places, were supplied from the same store
house. to say nothing of the immense quantities ex
ported to more distant points,, may realize the
Importance of the fisheries as bearing upon the qes
ton of national economy.
The larger portion, indeed nearly all, OF these ish
were anadronous species, such live for most of
the year in the sea and obtain the greater part OF
their growth there and up into fresh water for
the purpOse of spawning; among them the slad, the
alcwfc or fresh water herring the rocksh striped
bass, etc.
According to the tables prepared by Mr. Luding-
ton the slad supply was about onc-fourth less than
that for 1873, but the herring nearly double in
number. In 1874 there were ,2Gl II pounds more
fish inspected than in 1873. The inspector in this
report urges very strongly the regulation OF the cap
ture OF shad and herring in the Potomac River, 80
that none shall be taken after the LIST day of June in
any year. until the next regular fishing season, and
also that the hauling of the seine be prohibited Oh
Sunday al any tunc.
EXPLOSIVE AGENTS report of Prof. Abel on
OK plOsive agents applied to industrial purposes
delivered to the Institution of Civil Engineers, and
the discussions thereon during the past three years.
have been recently pablshed in pamphlet, from
which the following facts are taken;
Passing from the consideration Of gunpowder to
those substances that have been proposed substi
tutes therefor Prof Abel considers the three princ
pal ones as picric acid, nitrog and gun cot
ton.
Nitro-glycerine has been raised from the position
which it held for sixteen years, and appa-
rently useless chemical to that of most important
agent through the skill and perseverance,
of Mr. Nobel, who, in 1868, made public his PROPOSE
ton to add to the explosive power of guDpowder by
the grains with nitro Il cerinc. In
s84 Mr. Nobel described yeral methods of explod
ing charges of ntro-glycerine, and showed that the
explosion takes place with such great rapidity that
it il unnecessary to cOnine the charge by tampng,
or any other means. Nitro-glycerine is now extern
sivey employed not only in California but in Swo-
den, Germany, and Wales. The poisonous nature
of the exploding gases which lnjurousy affects the
health of those handling it, is of its defects. The
material is much less susceptible to accidental deto
nation in tho frozen than in ,he liquid condition
The accidents which have occurred with frozen
nitro lycerne appear tO have arisen from reck-
less of the material. The endeavors of Mr. Nobel
tn diminish the chances of the accidental explosion
of the liquid substance led to the production by him.
in 1867, of the solid preparation Of nitro
glycerine known under the name Of dynamite
which constituted, now manufactured one
Of the safesi, most powerful, aud most con-
venicnt explosive agents. Dynamite, ~ originally
prepared, consisted of about 75 per cent of
absorbed by about 25 per cent of
o porous, infusorial, scious earth found in Ger
many. This substance is now furnished TO tho
trade in cartridges whose charges have the con-
sstcncy Of dry putty During the late siege Paris
attempts made In that city to substitute some
other earth for that used in Germany. Tho most
efficient absOrbents were found TO DO silica
tripoli, alumina, and sugar. Mono Of thcse, how