Mechanical Science. 223 



paper-mills near Bath, has submitted to the Society of Arts 

 specimens of drawing-boards, which he calls Lino-Stereo tablets, 

 entirely free from these defects, and which have been found to 

 answer every trial made of them. The only material used in their 

 manufacture is the best and purest white linen rags, all muslins, 

 calicoes, and every other cotton article being rejected; and, 

 they are not composed of several sheets, but are moulded from 

 the pulp of any required thickness of one entire mass, so that 

 no separation of their parts can take place, either by wetting or 

 mouldiness. These tablets are made with either a rough or 

 smooth face, the former for drawings made with pencil, chalk, 

 or crayon, the latter for paintings in water-colours, or other 

 delicate works. They are also tinted of various shades of 

 drab-gray, sand-colour, ^c, the pulp being dyed in the vat 

 before it is made into tablets. — Trans. Soc. Art. xxxix. 43. 



9. New Green Pigment. — M. Bizio of Venice describes anew 

 pigment, obtained by boiling a hectogramme (1544 grains) of 

 cofFee-powder in water, reducing the infusion by evaporation to 

 eight hectogramme (28 oz. 4 dr.), adding an equal weight of 

 sulphate of copper dissolved in water, and precipitating by so- 

 lution of caustic soda. The deposit found weighed 105 

 grammes (1622 gr.); when dry, it was a fine green colour, and 

 the more exposed to air whilst moist, the brighter it became. 

 Water, ether, alcohol, and alkaline subcarbonates, had no ef- 

 fect upon it. Ammonia and potassa acted upon it : soda did 

 not alter it. It resists acids sufficiently well, and, with the 

 exception of the sulphuric and oxalic, no others destroy the 

 colour totally. They, however, dissolve it, and it is men- 

 tioned that acetic acid produces a solution with it of a very fine 

 green colour. 



10. Economical Matting. — Mr. Salisbury, with the intention 

 of giving employment to such as were destitute of it, engaged 

 a number of the paupers of the parish of St. George's, Hanover- 

 square, to collect a quantity of the typha latifolia (flag or greater 

 cat's tail), and to manufacture it into mats, baskets, hassocks, 

 chair bottoms, ^"c, with the intent of substituting it for the scir- 

 pus lacustris, or rush, which, though it grows abundantly in 

 some places, is by no means in sufficient quantity to supply 

 the demand made for it, so that large importations are made 

 from Holland. On a close comparison of the things made with 

 it, with those made with Dutch rushes, the work appeared ca- 

 pable of being made equally neat with either material, and an 

 examination of two pieces of matting, which had lain side by 

 side, and had their places changed occasionally, indicated that 

 they would wear equally. 



Hence the typha will probably afford a material of great use 



