96 
rorULAR SCIENCE REVIEW. 
amusing- myself, if any such apparently cruel occupation can be considered 
entertaining, in watching the capture of flies by the azaleas. When I first 
brought the flowers home, many small insects, as winged ants, were en- 
trapped amidst the hairs. These have remained alive several days, still 
vainly struggling for freedom. As the houseflies are abundant in my room, 
it occurred to me that I might extirpate the pests, and at the same time learn 
something of the process of insect-catching. I exposed a number of buds 
and fully opened blossoms on a sunny window-sill thronged with flies. It 
was not many minutes before I had several captures. A mere touch of a 
fly’s leg to the glutinous hairs was sufficient for his detention. A struggle 
only made matters worse, as other legs were by this means brought in con- 
tact with the glands. These emit long glairy threads which fasten to the 
hairs of the flies’ legs. They may be drawn out to a great length and 
tenuity, still retaining their strength. Under the microscope, the legs of the 
fly are seen to be covered with the secretion, which is perfectly white and 
transparent. In one attempt to escape, a housefly li fted a flower bodily from 
the window-sill, perhaps a quarter of an inch, but at once sank back ex- 
hausted amidst the hairs. In one instance, I have found the dried remains 
of a small insect embedded amidst the hairs, but cannot say whether its 
juices were in any way absorbed by the plant. 
CHEMISTRY. 
Marsh's and Reinsch's Tests for Arsenic combined. In the 11 Transactions of 
the Royal Society of Victoria, New South Wales ” [vol. x. 1874], which we 
have just received, there is a paper by the Rev. William Kelly, S.J., in 
which he explains a method which had suggested itself to him, by which 
Marsh’s test and Reinsch’s could be immediately combined, so as to ascer- 
tain and guarantee the absolute purity of the testing reagents, and to make 
the two great tests immediately corroborate each other. He relied on the 
well-known fact that the copper of Reinsch’s test is entirely dissolved in 
presence of Chlorate of Potassa, and pointed out that this action, which is 
often treated as an objection to the test, may be made to confirm it. If a 
portion or the entire of the copper thus completely dissolved be introduced 
into Marsh’s apparatus, it will produce the characteristic clouds, spots, and 
stains: the troublesome frothing incident to organic substances being en- 
tirely avoided. Pieces of porcelain and glass showing the results of experi- 
ments were handed round. The reverend gentleman explained in detail 
many of the advantages which would arise from this combination, which he 
believed had not been suggested in any of our toxicological treatises. 
The Manufacture of Otto of Roses . — In the u Moniteur Industriel Beige,” 
which is quoted by the u Scientific American” [October 10, 1874], is an 
interesting article on this costly perfume, which says that the manufacture 
is largely carried on in the valley of Kesanlik, Roumelia, the annual pro- 
duction of the rose farms of which amounts to 4,400 pounds of the otto per 
year* As it requires about 130,000 roses, weighing some 57 pounds, to 
make an ounce of the oil, some idea of the extent of the plantations may be 
