QUERIES.

[_We present herewith a series of inquiries embracing a variety of

topics of greater or less general interest. The questions are simple,

it is true, but we prefer to elicit practical answers from our

readers, and hope to be able to make this column of inquiries and

answers a popular and useful feature of the paper._]

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1.--EMERY WHEELS.--Can I make emery wheels similar to those used in

a foot lathe, that will answer for sharpening fine tools, such as

gouges, rounds, and hollows, and if so, how shall I proceed?--F. W.

2.--BOILER FURNACE.--I have two boilers, twenty-four feet long and

four feet in diameter each, with five ten-inch flues. The fire passes

under the boiler, and enters the flues at the back end, passes through

the flues, and enters the smoke stack at the front end. I use hard

pine wood for fuel. Will some of your many readers give me the best

way of constructing the flue under the boiler, from the end of the

grate bars to where it enters the flues at the back end, and also

state the proper distance from the back wall to the end of the

boiler?--N. H.

3.--MEDAL CASTS.--I have some medals which I should like to copy.

Having tried several times, and failed, I thought that I would ask

advice through your query columns. I do not know of what the medals

are manufactured. They are, I suppose, made to imitate bronze. I have

tried casting them in plaster of Paris molds, but have had very poor

success, as the surface of the medals was covered with small holes.

The metal used was lead and antimony, seven to one. I should like to

know, if there be any metal that I can cast them of, and bring out the

bronze color afterwards, or if there be any metal that I can cast them

of, and afterwards color by some solution. Also, of what should I make

my molds?--J. E. M.

4.--REMOVING THE TASTE OF TAR FROM RAIN WATER.--Will some of your

correspondents tell me if rain water, which runs off a gravel roof,

and tastes very strongly of tar, is unhealthy, and if there be

anything that will prevent its tasting, as it is very disagreeable for

cooking purposes?--C. E. H.

5.--SORGHUM MOLASSES.--How can I separate the molasses from the sugar,

in sorghum sugar mush, to make a dry merchantable sugar?

6.--FLUX FOR ALUMINUM.--Will some of your readers tell me, through

your columns, the best flux to use in melting and mixing aluminum and

copper?

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Scientific American, Volume XXIV., No. 12, March 18, 1871 A Weekly Journal of Practical Information, Art, Science, Mechanics, Chemistry, and Manufactures. · 第 113 / 194 题