108 
POPULAR SCIENCE REVIEW. 
Trinidad Asphaltum. — It seems that three varieties of this natural product 
were shown at the Paris Exhibition. These are derived from the Pitch 
Lake of Brea in Trinidad, which, says the Society of Arts Journal^ covers 100 
acres and yields enormous quantities of asphalte, whose value has not yet 
been recognised in Europe. Lacquer pitch, found in the vicinity of the Pitch 
Lake, is recommended as an ingredient entering into the composition of 
dark-coloured varnishes. Its commercial value is great, hut the supply is hy 
no means ample. Larger quantities may possibly be obtained by deep sink- 
ing. The export of asphalte from Trinidad in 1865 was 17,700 tons, princi- 
pally to Belgium, France, and England. One company in the island has 
entered into a contract to supply 1,500 tons yearly of asphalte, in blocks fit 
for paving, at nine dollars the ton, delivered on board. The same company 
has engaged to furnish a house at Antwerp with 20,000 tons at 50s. per ton, 
to extract oil from. 
MICROSCOPY. 
A ‘‘ Uve-hox ” for Tadpoles, which is both ingenious in conception and easily 
constructed, has been devised by Herr F. E. Schultze, and is described and 
figured in the Microscopical Journal for October. The object of such a 
contrivance is to enable the student to examine the circulation, &c., of the 
tadpole without placing the animal under artificial conditions. Here- 
tofore workers have employed a thick glass slide, into which a depression 
was ground, in which the object was placed. But as the grinding out of a 
hollow of this kind in a thick piece of glass would be attended with dif- 
ficulty, and consequently with considerable expense, Herr Schultze has 
always constructed the apparatus of three flat pieces of glass. The lower of 
these is nothing more than a common slide, and upon this, as a basis, the 
two others, in which the requisite incisions have been made, are affixed by 
means of Canada balsam (or marine glue). When used the hollow is filled 
with water, into which the animal is introduced, with its head beneath the 
anterior border, and the tail in the shallow depression at the other end, or 
on the surface of the glass, as the case may be, the whole being covered 
with thin glass in the usual way. 
A Novel Animalcule Cage has been invented by Mr. W. Moginie, in the 
establishment of Messrs. Baker, of Holborn. It is certainly a vast improve- 
ment upon the old live-box, and it is cheap and efficient. In constructing it 
Mr. Moginie grinds down to a fine surface a little brass hinge, enlarges its 
two screw-holes to about f of an inch, and then fastens one of its sides to an 
ordinary glass slide by means of marine glue. He next cements a piece of 
thin ‘‘ covering glass ” over the upper aperture in the hinge. The cage is 
thus ready for use. A drop of fluid containing the animalcules is placed in 
the aperture of that part of the hinge which is fixed to the slide, and which 
forms a sort of cell. The other portion of the hinge is then shut down on 
the fixed part, and this done, the slide may be placed under the microscope. 
Mr. Moginie’s invention we have found both convenient and effective. 
Microscope and Lamp-Stand. — In a recent number of the British Medical 
Journal, Dr. L. W. Sedgwick describes a contrivance for carrying both 
