6io 



THE POPULAR SCIENCE MONTHLY. 



For tlie purpose of,suspension an arrangement resembling a towel- 

 horse, with a single horizontal rail, will be found convenient. 



h. A straw, Z 7"', Fig. 2, delicately supported on the point of a 

 sewing-needle iV", inserted in a stick of sealing-wax A, attached below 



to a little circular plate of tin. 



In Fig. 



3 the straw is shown on a 



Fig. 2. 



larger scale, and separate from its needle. The short bit of straw in 

 the middle, which serves as a cap, is stuck on by sealing-wax. 



i. The name of " amalgam " is given to a mixture of mercury with 

 other metals. Experience has shown that the efficacy of a silk rubber 

 is vastly increased when it is smeared over with an amalgam formed 

 of one part by weight of tin, two of zinc, and six of mercury. A little 

 lard is to be first smeai'ed on the silk, and the amalgam is to be applied 

 to the lard. The amalgam, if hard, must be pounded or bruised with a 

 pestle or a hammer until it is soft. You can purchase sixpennyworth 

 of it at a philosophical-instrument maker's. It is to be added to your 

 materials. 



''"'' ^ipfi 



s' 



I 



Fig. 3 



k, I should like to make these pages suitable for boys without 

 much pocket-money, and therefore aim at economy in my list of 

 materials. But provide by all means, if you can, a fox's brush, such 

 as those usually employed in dusting furniture. 



Sec. 5. Electric Attractions. Place your sealing-wax, gutta-percha 



