and Processes in the Useful Arts. 151 



ter, and then washed clean. Two or three coats of varnish being ap- 

 plied to the leather, &c. and each coat permitted to dry for two or three 

 days, a brilliancy equal to that of Japan lacker will be produced. — Bul- 

 letin de la Societe d' Encouragement, §c. or Gill's Tech. Repos. May 1824, 

 p. 320. 



6. Siemens Improvement on the Process of making Brandy from 



Potatoes. 



The introduction of this process, which has been adopted in many 

 parts of Germany and in the north of Europe, has been recommended to 

 the Swedish government by M. Berzelius, and to the Danish govern- 

 ment by Professor Oersted. From the trials made at Copenhagen, it 

 would appear that one-third more brandy is produced than by the usual 

 processes. In Professor Oersted's report, we find the following account 

 of the process. The potatoes are put into a close wooden vessel, and ex- 

 posed to the action of steam, which heats them more than boiling water. 

 The potatoes can thus be reduced to the state of the finest paste with the 

 greatest facility, it being necessary only to stir them with an iron instru- 

 ment furnished with cross pieces. Boiling water is then added to the 

 paste, and afterwards a little potash, rendered caustic by quicklime. 

 This dissolves the vegetable albumen which opposes the complete con- 

 version of the potato starch into a fluid. Professor Oersted frees the 

 potato brandy from its peculiar flavour by means of the chlorate of 

 potash, which is said to make it equal to the best brandy made from 

 wine.— Gill's Tech. Repos. No. 29, p. 322. 



7. Account of Improvements on Thin Circular Saws. 



In order to prevent thin circular saws from bending, or buckling as it 

 is termed, they are generally confined between two flat circular plates. 

 The improved method, however, consists in confining the binding to a 

 more narrow ring near the periphery or rim of the saw. By this simple 

 contrivance, the saw revolves with such truth and accuracy that it is fit 

 for the nicest operations, such as cutting the teeth of the finest combs. 

 The gentleman who communicated to Mr. Gill this contrivance, always 

 softens his circular saws when their teeth require sharpening, which great- 

 ly facilitates the operation. He tempers them only to a yellow colour, 

 by which they last much longer than when they are tempered to the 

 spring temper. Mr. Gill likewise mentions, that the late Mr. S. Varley 

 prevented the very common evil of the bending of the saw-arbor, which 

 arises from the imperfection of the screw upon it, by forming the exter- 

 nal face of one of the circular plates convex, and the face of the binding 

 screwed nut concave ; both being portions of spheres of the same diame- 

 ter. They were thus allowed to ply or yield to the irregularity of the 

 screw, which could not take place when their surfaces were made flat as 

 usual. — See Gill's Tech. Repos. No. 31, p. 64. 



8. On tlie Invention of Floating Breakwaters. 

 We have much pleasure in inserting the following article, which is the 



