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. 



