L. TECHNOLOGY. 467 



by which the oil is extracted is not indicated ; nor is the rea- 

 son given why the value of the product should be so great, 

 compared with that of nearly all the other animal oils in mar- 

 ket. It is much to be. regretted that this new mode of exter- 

 mination of our coast birds should have been initiated, and 

 it may well be asked whether it is not the duty of the proper 

 authorities to pass stringent laws prohibiting this practice. 

 14 A, June, 1871, 1006. 



LUBRICATING OIL. 



It is well known that in the friction of two surfaces to- 

 gether a certain amount of heat is produced, and that the 

 office of a lubricator is to reduce this friction to a minimum 

 by filling up the inequalities of the surfaces, and preventing 

 their adhesion. The more completely this is done, the less 

 heat is developed ; or, in other words, the less heat produced 

 by the mutual friction of two oiled surfaces in a given time, 

 so much more valuable is the lubricator made use of. Upon 

 this principle, a machine has lately been constructed for test- 

 ing the comparative merits of lubricating oils, in which the 

 amount of heat developed in a given time by a certain num- 

 ber of rotations, with oils of different qualities, is measured 

 on an attached thermometer, and it is said that this appara- 

 tus is now largely used in various establishments for the pur- 

 pose of furnishing the test in question. 5 (7, n., 15. 



REMOVAL OF LACQUER, OR LEATHER, FROM TINNED IRON. 



According to Dr. Emsman, the adhesion of the lacquering 

 upon articles of tinned iron, or ordinary tin, or of a leather 

 covering on tin, may be destroyed in a very short time by 

 making a cut through the substance of the coating, and ap- 

 plying a small quantity of mercury. This is rapidly taken 

 up, and forms a soft amalgam with the tin under the outer 

 layer, and allows the latter to be lifted off without difficulty. 

 14 6 Y ,CXCVIII.,164. 



LACQUERING VARNISH. 



A varnish recommended as well adapted for lacquering pic- 

 tures and engravings, as well as for preserving dried plants 

 and flowers, is prepared by pounding up ten ounces of gum 

 sandarac, four ounces of mastic, and half an ounce of camphor, 



