Page:Popular Science Monthly Volume 92.djvu/593

 Popular Science Monl/ih/

��Detecting Glucose in Jellies, Jams, and Kindred Confections

GLUCOSE in fruit preserves may be discovered as follows: In the case of jelly a teaspoonful should be dissolved in two tablespoon- fuls of alcohol con- tained in a glass vessel. In the case of jam or marma- lade the same proc- ess is carried out, but it is necessary to filter off the solid matter by run- ning the mixture through a piece of muslin. Allow the solution to become

���This simple apparatus will enable you to detect the presence of glucose in jam and marmalade

��perfectly cool, and then add an equal volume, or a little more, of strong alcohol. If glucose is present a dense white pre- cipitate slowly settles down. Where no glucose has been employed there is no precipitate, save, in some cases, a very trifiing sediment of proteid matter which, however, is so small that it could not possibly be mistaken for the sediment which glucose produces. The last-named is not particularly harmful in it- self, but it is very frequently used as an adulterant in supposedly pure preserves for extra profit.

��r>77

Chain Your Automobile to a Hydrant If the Electric Lock Doesn't Hold

ADMITTEDLY, the stealing of auto- L mol)iles has become a serious prob- lem. John F. Hen- drickson of Wollas- ton, Mass;, would prevent it by in- stalling on every car an electric lock. This shuts off igni- tion circuits, cur- rent to the starting motor, and also locks the steering wheel when the owner withdraws the key and leaves the machine.

The circuits are too complicated to

���A complicated electric lock, designed to thwart attempts to steal an automobile

��reproduce in detail here, and also vary with the make of car. The contacts in- side the electric lock are so arranged that, by resetting certain pins, at any time it is possible to change the combination and thus foil the thieving proclivities of a chauffeur or other person who has almost familiarized himself with the system and is about to make a get-away with the car. Elaborate auxiliary devices are also pro- vided to prevent unauthorized re- al of any parts of the system I an attempt to get at the inner wiring.

Contrivances such as this, though commend- able in their effort, prac- tically all fall down be- cause the feat is almost impossible. It is always possible to get at inner wiring in one way or another, and a knowing thief can soon devise im- promptu wiring that will ork. It is an axiom among burglars that the simplest and rustiest old locks are the most baf- About the only way effectively to make an automobile stay in the place where you left it, against all comers, is to insert a long piece of railroad rail between the spokes of the hind wheels and chain it to a convenient hydrant — and then there would be sure to be a fire.

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