MECHANICS AND USEFUL ARTS. 123 



from the pure crystallized, but from an inferior kind of picric 

 acid, and is probably destined to replace the archil in many cases, 

 in imparting to wool all shades, from garnet to chestnut-brown. 

 It may be readily combined with other pigments, so that a num- 

 ber of different colors may be obtained. According to Casthelaz, 

 the dyeing of wool and of silk is effected by the addition of an or- 

 ganic acid to the bath, for instance, acetic or tartaric acid, min- 

 eral acids being excluded. The dye-bath for silk should be cold 

 or tepid in the beginning. Different shades in red and brown are 

 thus obtained that are dependent upon the concentration of the 

 bath, the nature of the mordant, and the time of the operation. 

 Nature. 



FIBROUS COTTON-SEED. 



Mr. Thomas Rose read a paper at the meeting of the British 

 Association, "On the Utilization of Fibrous Cotton-Seed.'' He said 

 that a vegetable production, which should be valuable, and could 

 be supplied to the extent of millions of tons, was now wasted. 

 The waste product was fibrous cotton-seed, and in America alone 

 more than a million and a half tons of the seed were wasted 

 yearly. The seed was composed of 50 per cent, kernel, which 

 yielded about one-third oil, and 50 per cent, husk-shell with fibre 

 adhering, of which the fibre would be one-third. His calcula- 

 tion was that the waste seeds would produce 250,000 tons of pure 

 cotton, 250,000 tons of oil, and 500,000 tons of cattle-cake, the 

 value of which he estimated at 20,000,000 sterling. The husks 

 could be taken to the paper-mill and the cotton abstracted in such 

 a manner as to form a most valuable material for paper. There 

 was a process by which the cotton fibre could be completely sep- 

 arated from the shell ; and the seed had a chief advantage, that 

 of unfailing supply. In conclusion, Mr. Rose remarked upon the 

 value and use of the oil and the cattle-cake that would be yielded 

 by the seed. 



EQUILATERAL TRIANGULAR DRAWING-BOARD FOR ISOMETRICAL 



DRAWING. 



Mr. George Fawcus, of North Shields, has contrived an equi- 

 lateral triangular drawing-board for isometrical drawing. An 

 ordinary T square applied on the edges of an equilateral triangle 

 draws tangents that meet each other at angles of 120, and other 

 lines drawn parallel to these radiating ones form with them angles 

 of GO and 120, which are the exact angles of the apparent 

 square of isometrical cubes. The inventor "believes that the use 

 of this new drawing-board will make the teaching of isometrical 

 drawing both simple and easy. The practice of isometrical 

 drawing is strongly urged in the science and art drawing classes. 

 Nature. 



