Queries. 
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Correspondents, in sending us answers to questions, are desired to commence 
by quoting the number and title of the question as printed, before beginning their 
reply. All answers should reach us before the 12th of the month. 
335.—Double-pointed Entomological Pins.—_In C. G. Calwer’s 
“ Kaserbuch,” a method is recommended of setting Coleoptera on 
the top of double-pointed pins (Zweispitzige nadel), the points of 
which are sharp and tapering. Small beetles are empaled on the 
very tip of the pin, while in the case of the larger species a greater 
length of point goes into the insect, and thus only one size of pin is 
required. Even small species, such as the Cryptophagi, can be 
thus pinned, and the method has this superiority over sticking on 
card with gum-tragacanth: that the card is apt to turn brown or 
curl up in course of time. But Calwer gives no information as to 
where these pins may be obtained. Can any reader of the 
Enquirer inform me on this point ? G: Ficge: 
336.—Multiplied Images in Eye of Beetle.—Will some of our 
readers tell me how to place an object that I may see it multiplied 
in the eye of a beetle under the microscope ? W pe 
337.—Etching on Glass.— How are ornamental designs etched 
or embossed on glass ? JN. 
338.—Soap-Bubbles.—I have read or heard of soap-bubbles 
which will last for several hours in the open air, but cannot turn 
up a reference to them anywhere. Will some friend help me? D. 
339.—Why Flowers turn White.—Could any of your readers 
explain the reason of some flowers turning white, such as the fox- 
glove, when brought into a garden? M. F. 
340.—Blue Flame produced by Salt.—If common salt is 
sprinkled over glowing coals, it produces a purple or bluish, not 
yellow, flame. What is the reason of this? Is it due to absorp- 
tion of the yellow rays given out by the coals owing to the sodium 
vapour being at a lower temperature than they are? 
G) B2C.. SEARLE, (Bra. 
341.—Hoar Frost.—Why is it that the hoar frost deposited on 
the windows in cold weather sometimes arranges itself in beautiful 
geometrical crystals, while at others the crystals are so small as to 
form merely a dull white covering on the surface of the glass ? 
EB EIDDES: 
342.—Chill at Sunrise.—What is the reason that at sunrise the 
air seems so frequently to turn suddenly colder and remain so till 
the sun’s warmth begins to be felt ? E. FIDDEs. 
