March, 1911 
THE JUDGING OF RUBBER GOODS 
N the above subject the Gummizei- 
tung says: The determination of 
the quality of rubber goods is often 
effected from entirely erroneous view- 
points. Thus, for instance, the opinion 
prevails that the softest qualities are the 
best, which in the case of certain combi- 
nations, for tough hose, or valves, is by 
no means the case. It is just as wrong to 
draw conclusions as to the quality of the 
goods from their color or to base a judg- 
ment on energetic pulling and blending 
tests. This opens the door to mistaken 
conclusion. If we can bend a semi-cir- 
cular formed hard rubber child’s comb of 
very thin make, out flat, its quality will 
be recognized as excellent; a similar ex- 
periment cannot be conducted with an 
equally good comb, of heavier make, 
without breaking the object of the ex- 
periment, which would then erroneously 
be regarded as of inferior quality. There 
are many such cases. Widespread also 
is the misunderstanding of the term 
‘Para rubber;” it includes, as far as the 
technically uninformed are concerned 
the idea of a high-class caoutchouc 
adapted for all purposes. That Para 
rubber cannot be used for all purposes, 
would only, in rare cases, find credence; 
the objection that some goods, whether 
for practical reasons or only for consid- 
erations of price, must be produced more 
or less with the aid of surrogates or fill- 
ings, and can then no longer, in accord- 
ance with commercial requirements, be 
designated Para quality, would often 
awaken doubts. 
THE SPEAKING CLOCK 
HERE is nothing outwardly _remark- 
able, according to Das Echo, in the 
appearance of the ingeniously con- 
structed timepiece known as the “time- 
stating clock.” But every quarter of an 
hour an agreeable voice issues from it, 
announcing the correct time, as, twelve 
o'clock, twelve fifteen, twelve thirty, etc. 
The works of the clock actuate a stout 
belt, which runs over a roll connected with 
a sounding box. 
Upon this belt, or rather film, the hours, 
which have been recorded by a phonograph 
are impressed by galvanization on a copper 
plate. 
The mechanism which moves the hands 
is connected with the speaking device, and 
this with a funnel which reinforces the 
sound and projects it outward through a 
finely grated opening attached to the nar- 
row side of the clock. 
At night a touch on a lever reduces the 
clock to silence. But if one wakes and 
wishes to know the hour without striking a 
light, an easily found button is pressed and 
the clock immediately states the time. 
The speech film is practically indestruct- 
ible and occupies very little space since, be- 
cause of its elasticity, it may be wound 
upon a very small roller. 
CURES FOR WARTS 
LYSCHUL recommends as a remedy 
for this very obstinate trouble, the 
ointment described by Unna, made 
of gray mercury salve, with the addition of 
5 to 10 per cent. of arsenic. The salve 
should be smeared on lint and made fast to 
the wart by bandages. Finally painting 
with tar may be resorted to. The remedy 
is very poisonous. 
AMERICAN HOMES AND GARDENS XXxI 
Coldwell Lawn Mowers 
Hand, Horse and Motor 
Coldwell’s Motor Lawn Mowers 
Will do the work of three horse 
lawn mowers—and do it better 
q They will mow up 20 per cent grades. 
no hoof-prints as horses do. 
smoothly. 
men and three horses. 
when not in use. 
economical. 
@ They leave 
@ They will roll the lawn 
@ They do away with the expense of two 
@ They are of no expense 
@ They are simple to operate and 
q They are a necessity on every large lawn 
Catalogue sent on request 
Manufactured by 
Coldwell Lawn Mower Co. 
Newburgh, N. Y. 
The Cost of Manufacturing Denaturized Alcohol in Germany and 
German Methods of Denaturization are discussed by Consul-General 
Frank H. Mason in Sczentific American Supplement 1550. 
The Use, Cost and Efficiency of Alcohol as a Fuel for Gas Engines 
are ably explained by H. Diederichs in Scren(ific American Supple- 
ment 1596. Many clear diagrams accompany the text. The article con- 
siders the fuel value and physical properties of alcohol, and gives details 
of the alcohol engine wherever they may be different from those of a 
gasoline or crude oil motor 
In Scientific American Supplement 1581 the Production of In- 
dustrial Alcohol and its Use in Explosive Motors are treated at length, 
valuable statistics being given of the cost of manufacturing alcohol from 
farm products and using it in engines. 
French Methods of Denaturization constitute the subject of a good 
article published in Sczentific American Supplement 1599. 
How Industrial Alcohol is Made and Used is told very fully and 
clearly in No. 3, Vol. 95, of the Sczentific American. 
The most complete treatise on the Modern Manufacture of Alcohol, 
explaining thoroughly the chemical principles which underlie the pro- 
cess without too many wearisome technical phrases, and describing and 
illustrating all the apparatus required in an alcohol plant is published in 
Scientific American Supplements 1603, 1604 and 1605. The 
article is by L. Baudry de Saunier, the well-known French authority. 
ALCOHOL 
Send for Our New 1910 Supplement Catalogue. 
Its Manufacture 
Its Denaturization 
Its Industrial Use 
In Supplements 1607, 1608, 1609 we publish a digest of the rules 
and regulations under which the U. S Internal Revenue will permit 
the manufacture and denaturation of tax free alcohol. 
A comparison of the Use of Alcohol and Gasoline in Farm Engines 
is given in Sclentific American Supplements 1634 and 1635 by 
Prof. Charles E. Lucke and S. M. Woodward. 
The Manufacture, Denaturing and the Technical and Chemical 
Utilization of Alcohol is ably discussed in the Sczentific American 
Supplements 1636 and 1637 by M. Klar and F. H. Meyer, both ex 
perts inthe chemistry and distillation of alcohol. Illustrations of stills 
and plants accompany the text 
The Sources of Industrial Alcohol, that is the Farm Products from 
which alcohol is distilled, are enumerated by Dr. H. W. Wiley in 
Screntific American Supplements 1611 and 1612 and their relative 
alcohol content compared. 
The Distillation and Rectification of Alcohol is the title of a splendid 
article by the late Max Maercker (the greatest authority on alcohol) pub- 
lished in Sczentific American Supplements 1627 and 1628. Dia- 
grams of the various types of stills in common use are used as illustrations 
In Screntjfic American Supplement 1613 the Uses of Industrial 
Alcohol in the Arts and in the Home are discussed. 
Any Single Number of the Sczen/ific American or Supplement 
will be sent for 10 cents by mail. The entire set of papers above listed 
will be mailed on receipt of $2.00. 
FREE to Any Address. 
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