8 farmers' and mechanics' journal. 



different kinds. Some of ihe resins employed, possess one of these 

 properties, and some another ; from this cause, they are frequently 

 used in a state of combination ; a portion of hardness, and of tough- 

 ness, is frequently sacrificed, to obtain brilliancy. Common rosin, 

 which is the most brittle of all the resins, will communicate a high 

 degree of brilliancy to some of the others ; it ought, however, to 

 be very sparingly employed, as it in other respects, deteriorates 

 the varnish. Jt is very cheap, and easily dissolved, and, from these 

 causes the manufacturer of varnishes, not unfrequently, uses it too 

 freely, to the great injury of the consumer. The toughness of a 

 varnish depends, not only on the kind of resin employed, but also 

 on the solvent. The oil varnishes are the toughest, as the oils 

 themselves, when dried, form very tough, and sometimes very good 

 varnishes, without the addition of any resinous matter. 



Varnishes differ greatly in the time required to dry them. Some 

 of the resins retain the spirit in which they are dissolved, much 

 more powerfully than others ; the spirit varnishes, however, dry 

 the most readily ; some of them, in favorable weather, hardening 

 almost as quickly as they can be laid on. The oil varnishes re- 

 quire a greater length of time, than those made with spirit, and the 

 same kind differs greatly in different specimens. Copal, with lin- 

 seed oil, will sometimes dry perfectly in an hour or two, whilst 

 other portions will require many days, and even weeks, before they 

 are perfectly hard ; as this arises from a difference in the oil, it is 

 a point of manifest importance, to understand the cause of these 

 differences, so as to be able to produce, at all times, such an arti- 

 cle as may be wanted. We have, in this paper, made those gene- 

 ral remarks, which appeared to be necessary to a right understand- 

 ing of the subject ; the whole article will be of considerable ex- 

 tent, and excepting from some accidental cause, every succeeding 

 number of the Journal will contain an essay, until a complete 

 treatise has been furnished. 



ON THE USE OF SOAPSTONE 



TO DIMINISH THE FRICTIOM OF MACHINERY. 



I have observed in the July number of the Franklin Journal, 

 a short article copied from the Edinburgh JmirnaL in which refer- 

 ence is made to this use of soapstone. The fact is simply stated, 

 that " it facilitates the action of screws, and from its unctuosity, 

 may be employed with much advantage, foi- diminishing the fric- 

 tion of the parts of machines which are made of metal." 



1 understand that soapstone has been used for this purpose in 

 the extensive mannfactories 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 adapted to the use for which it is de- 

 signed. It is of course, important to procure that which is free 



