THE Microscope. 91 
ficient to produce iridescence, just as “ Newton’s rings” are 
formed by two pieces of glass when they touch. That the 
colors are in more or less regular waves confirms this explana- 
tion. H. M. J. UNDERHILL. 
Cieantne Surpes.—I. Make a solution of Hudson’s Extract 
of Soap, immerse the slides, and leave for a few days; the 
balsam, cement, and everything else will clean off beautifully. 
It is preferable to using vitriol or other strong acids. 
J. W. GRovEs. 
II. 1 find the following solution very good for new or old 
slides and cover-glasses:—Bichromate of Potash, 2 ozs.; sul- 
phuric acid, 3 fluid ozs.; water, 35 fluid ozs. Cover them com- 
pletely with the brown fluid, rinse under a tap, and stand on 
edge on several thicknesses of blotting-paper. Before mount- 
ing on them, the dust should be brushed off with a camel’s-hair 
brush. For new covers, place a few in a wide-mouthed bottle, 
cover with the solution, shake often so as to separate them. 
After three or four hours, pour off acid solution, and wash the 
covers in a bottle with water, pouring on and off until the water 
is colorless. When wanted, a cover’can be taken out of the 
bottle with a pair of forceps and wiped dry with a linen rag. 
This plan is useful for even the thinnest covers. Weve, 
ON THE ORANGE INSEcTS.—When a dish of oranges is seen 
onthe table at dessert, the fact is hardly realized that in all 
probability their surface is the habitat of an insect of the Coc- 
cus family. ‘This tiny creature is found on the orange skin in 
every stage of transformation, from the egg to the perfect in- 
sect, during the winter months, instead of remaining dormant 
in the cold weather, as is the case with most of this insect tribe. 
It would hardly be possible to find a St. Michael’s or Tangierin 
orange that had not hundreds of these little creatures, in vari- 
ous stages of development, on its surface. Lemons, too, are fre. 
quently covered. Upon inspection, the skin of an orange wil} 
be found to be dotted over with brownish-scarlet spots of yari- 
ous sizes. These specks can easily be remayed with 4 needle, 
and when placed under a microscope an interesting scene is pre- 
sented, consisting of a large number of eggs, which are oval, 
white bodies, standing on end, like little bags of flour, some of 
