Mechanical Science, 455 



lating about the glass, is confined to the part where the separation 

 is desired. As soon as the cord smokes, the glass is plunged 

 in water, or if too large to be easily immersed, the water must be 

 thrown upon it ; the latter method is always preferable when, 

 upon immersing the body, the water can reach the inner surface. 

 As plunging is the most effectual method of employing the water 

 in the case of a tube, I usually close the end which is to be im^ 

 jnersed/'^— (St7/ima/i*« Journal^ xiii. 7. 



5. Use of Soapstone in diminishing Friction. — In a letter to 

 Professor Silliman upon this subject, Mr. E. Bailey of Boston, 

 says, " I understand the Soapstone has been used for this purpose 

 in the extensive manufactories at Lowell, for about two years, and 

 with great profit and success. Besides answering the purpose to 

 which it is applied very much better than any other substance that 

 can be procured, it saves a great deal of trouble and expense. It 

 is first thoroughly pulverized, and then mixed with oil, tallow, lard, 

 or tar, whichever may be the best adapted to the use for which it is 

 designed. It is of course important to procure that which is free 

 from grity and it can be purified in a good degree by mixing the 

 powder with oil, and decanting it after it has stood a few minutes. 

 The heavier particles will form a sediment to be rejected. It is 

 used in all kinds of machinery where it is necessary to apply any 

 unctuous substance to diminish friction, and it is said to be an 

 excellent substitute for the usual composition applied to carriage- 

 wheels. 



Some idea of the value of soapstone thus applied, maybe formed 

 from the following fact communicated by D. Moody, Esq., the 

 superintendent of the tar-works on the mill-dam near this city. 

 Connected with the rolling machine of that establishment, there is 

 a horizontal balance-wheel, weighing ybwr^ee;i tons, which runs on 

 a step of five inches diameter, and makes from seventy-five to one 

 hundred revolutions in a minute. About one hundred tons of iron 

 are rolled in this machine in a month ; yet the wheel has some- 

 times been used from three to five weeks without inconvenience, 

 before the soapstone has been renewed. The superintendent thinks, 

 however, that it ought to be more frequently employed. 



*' The use of soapstone was discovered at Lowell. It has been 

 said never to fail in producing the desired result when applied 

 to machinery which had began to be heated, even in those cases 

 when nothing else could be found that would answer the pur* 

 pose." — Silliman* 8 Joumaly xiii. 192. 



6. On peculiar Physical RepulsionSy by M. Saigey. — I intend to 

 give in this bulletin the description of a very simple apparatus, by 

 means of which I have made many experiments, which have con- 

 ducted me to the following results : — 



i. All bodies exert between themselves a feeble repulsive action 

 in ordinary circumstances. The repulsion between bismuth and 



