Answers to Queries. 97 
338—Soap-Bubbles.—M. Plateau gives the following recipe :— 
“‘ First, dissolve 1 part by weight of Marseilles soap cut into thin 
slices in 4o parts of distilled water and filter. 2nd, mix 2 parts by 
measure of pure glycerine with 1 part of the above solution in a 
terperature of 66° Fahr., and after shaking them long and 
violently leave them at rest for some days. A clear liquid will 
settle with a turbid one above. ‘The lower one is to be sucked 
out from beneath the upper with a syphon, taking the utmost care 
not to carry down any of the latter to mix with the clear liquid. 
A bubble blown with this will last several hours, even in the open 
air. Or the mixed liquid, after standing twenty-four hours, may 
be filtered.—frvom Sir John Herschel’s “ Familiar Lectures on 
Scientific Subjects,” 1867, p. 287. GH. B: 
339.—Why Flowers turn White.—Flowers which are not 
green owe their colours to a series of compounds, which are but 
little understood, but which have been to some extent classified 
by means of the spectroscope. The changes in colour which 
many flowers undergo are supposed to be owing to oxidation of 
these bodies—e.g., the Garden Convolvulus turns from pink to 
purple during its expansion. Cultivation effects great changes in 
this respect, but has a limited influence. Some naturally yellow 
flowers, such as the Tulip and the Dahlias, assume all shades of 
red, orange, and white, but not of blue; while Geraniums will 
acquire various shades of blue, purple, red, and white, but no 
yellow. Hence, plants have been divided into two series— 
Xanthic, having yellow for a base; and Cyazzc, having blue. Either 
may become red or white, but cannot assume the basic colour of 
the other. JA. OGG. 
343.—To destroy Beetles.—A solution of sulphide of potas- 
sium (4 oz. to 1 gallon) has been very highly recommended in the 
“Garden” during the last few weeks, as an unfailing remedy 
against mildew, blight, and insects of all kinds in plants. It 
might be worth trying in this case. lle Bee adsloree: 
345.—Parasites on Hedgehogs.—The hedgehog flea (Pulex 
ertnaceus) is not uncommon. The hedgehog tick (Zxodes hexagonus) 
has a whitish body, with a hexagonal shield. Another species 
(Lxodes megatherius) is also found. It is of a brown colour, with 
an obovate shield. 
346.—Flies and Pedestrians.—If the face and neck be 
sponged with elder-flower water (obtainable from any chemist), 
very little annoyance will be felt from the attacks of summer 
insects. ieee Toce 
349.—Lissagou’s Curves.—I think E. B. will find the kalei- 
dophone, invented by Wheatstone, better for tracing these curves 
