332 PHILOSOPHICAL TRANSACTIONS. [anNO 1750. 



came off; but washing with a soft hair pencil dipped in water, and letting it dry 

 without wiping, the colours stood very well, A board, painted as in Exp. 8, was 

 hung m the most smoaky part of a chimney for a day, and exposed to the open air 

 in a very foggy night. In the morning the board was seemingly wet through, and 

 the water ran off the picture. This was suffered to dry without wiping, and the 

 picture had not suffered at all from the smoke of the dew, either in the ground 

 or the colours : but when dry, by rubbing it first with a soft cbth, and after- 

 wards with a brush, it recovered its former gloss. 



Suspecting that some tallow might have been mixed with the white wax he 

 had used, which might cause the colours to come off on being rubbed with a 

 wet cloth, he took yellow wax which had been melted from the honeycomb in a 

 private family, and consequently not at all adulterated ; to 3 parts of this he 

 added one part resin, and melted them together. 



Exper. 9. — Spanish white, mixed with fish glue, was put for a ground on a 

 board and painted with water colours only. The board was made warm ; and 

 then the wax and resin were put on with a brush, and kept close to the fire till 

 the picture had imbibed all the varnish, and looked dry. When cold, he rubbed 

 it first with a linen cloth, and then polished it with a hard brush. 



IX. On the Success of the preceding Experiment, hi a Letter from Mr. Josiah 



Colebrook, F. R. S. p. 53. 



This short letter accompanies a specimen of the encaustic on paper, being a 

 bird drawn by Mr. George Edwards, on paper prepared with a ground of whiten- 

 ing and fish-glue, painted with water colours, and then the wax, &c. burned 

 in. This will roll up as easily as common paper, without cracking the varnish. 

 There are also 2 landscapes, painted by a young lady, after the same manner, on 

 wood. 



X. Of a Particular Species of Cocoon * or Silk Pody from America. By the 



Rev. Samuel Pullein, M. A. p. 54. 



Having lately seen the aurelia of a particular species of caterpillar, Mr. P. 

 judged, from its texture and consistence, that there might be procured from it 

 a silk not inferior to that of the common silk-worm in its quality, and in its 

 quantity much superior. He made some experiments on this new species of silk 

 pod, which strengthen this opinion. This pod is about 3^ inches in length, and 

 above one inch in diameter ; its outward form not so regular an oval as that of 

 the common silk worm ; its consistence somewhat like that of a dried bladder, 

 when not fully blown; its colour of a reddish brown; its weight 21 grains. 



* Several of the large moths of the Linnean division attaci form similar pods, in which they un- 

 dergo their chrysalis state, as the phalaena Atlas, Hesperus, &c. 



