sea through the jetties is one
thousand feet wide, and through the works at the head of the Pass
eight hundred feet.

A recent telegram from Nevada states that the Sutro Tunnel (of which I
gave you some particulars in one of my letters) has now progressed a
total distance of 15,565 feet and has fairly entered the mineral belt,
and will soon help to increase the already vast products of the
Comstock lode.

While on the subject of mining, I will state that the amount of
quicksilver produced in California has increased so immensely during
the last two years that it has attracted the attention of all
interested in the article throughout the world. The receipts for the
year have been 63,928 and the exports 48,010 flasks. In addition to
the receipts there, probably about six thousand flasks were shipped
direct from the mines to Nevada, thus bringing up the total production
to over 70,000 flasks, a gain in round numbers of from twelve thousand
to fifteen thousand flasks over 1875. The exports in that year were
34,844 flasks, or 13,666 less than in 1876.

Occasional.

* * * * *

TYRIAN PURPLE INK FOR MARKING LINEN.--Von Bele gives the following
method for preparing an ink for marking linen and cotton: Neutralize
75 grains of carbonate of ammonia with pure nitric acid, and triturate
45 to 60 grains of carmine with the solution. Mordant the fabric with
a mixed solution of acetate of alumina and tin salt, and write upon
it, when it is perfectly dry, with the ink.

* * * * *

NEW YORK ACADEMY OF SCIENCES.

On Monday evening, January 29, 1877, a meeting of this Academy was
held at the School of Mines, Columbia College, Dr. J.S. Newberry,
President, in the chair. Mr. A.A. Julian, A.M., read a paper on the

PREPARATION OF ROCK AND MINERAL SECTIONS FOR MICROSCOPIC STUDY.

The speaker described in detail the various operations, exhibited the
different kinds of apparatus employed, showed the operations, and
exhibited the finished sections. In some rocks a thin chip can be
broken off, others require to be sawn, and for the latter purpose the
diamond saw is best. Having obtained the chip, it is first polished on
one side, then cemented to a little square of glass, and the other
side polished in the same way. The sections must not be too thick, nor
too thin; they are usually made from a hundredth to a thousandth of a