1878. ] Scientific News. 841 
ing as the object to be shown is white or black. It may be ṣẹ of 
an inch in diameter for the Lieberkühn of the 14 inch objective, 
but not over } inch for that of the 2 objective. After the cement 
is dry and quite hard, a thin coat of balsam is spread over it and 
the objects placed in this and arranged if necessary under the 
microscope. The slide is then set aside to dry and may safely be 
covered the next day. If the object to be mounted will bear 
immersion in balsam, as some shells, seeds, minerals, etc., I pur- 
sue the following plan: The thin glass covers are cemented to 
some old slips, kept for the purpose, by two or three touches ot 
the balsam applied to the edge of the cover, care being taken to 
center the cover on the slip by means of the self centering turn- 
table. The objects are then arranged on a light coating of bal- 
sam on the center of the cover. When quite dry they should be 
completely covered by balsam and thoroughly hardened in the 
drying oven. Then Brunswick black or white zinc may be 
spread over the object, in thin layers at first, each being dried in 
the open air for a day before putting on the next, until an opaque 
covering: is made for the object. Thoroughly clean the cover 
around the objects and then remove it from the slip by a slight 
heating. Then turn it over and mount it upon the cell prepared 
for it. Fasten the cover to the cell with gelatine softened 
water to the consistency of jelly and then liquified by alcohol. 
Put the cover on the cell and apply the gelatine solution with a 
brush around the edge, leaving the little opening before referred to. 
When dry the cell may be finished with liquid balsam, carefully 
avoiding the little aperture. The outer edge may be gathered up 
into a neat trim circle with the point of a knife on the turn-table. 
C. Merriman, Rochester, New York. ‘(Read at the National 
Aedini Congress at Indianapolis, August, 1878.) 
SCIENTIFIC NEWS. 
— BRITISH ASSOCIATION FOR THE ADVANCEMENT OF SCIENCE. 
We conclude our account of the last meeting, which was, on the 
held for twenty years. Several of our American scientists read 
papers. Prof. terry Hunt made communications on the 
Metamorphic or “Archean rocks of America as compared with 
those of Great Britain, and also on the geological relations 
of the atmosphere. Prof. E. D. Cope read papers on the Sauri- 
ans of the Dakota formation of the Rocky mountains, and on 
the Vertebrata of the Permian formation of Texas. Mr. Graham 
Bell made a communication on the Telephone. Prof. Cook, 
i State-geologist of New Jersey, was also present. Of the papers 
of special interest, we note one in the zoôlogical section by Sir 
-Victor Brooke on the deer; a good point he made was the exis- 
tence of a constant yarmtion in the horn of Cervus dama, which 
