fl,l8 Acllon of fame lately d'tfcovered "Nletals and Earths 



Exp. IX. A fokition of arfeniate of foda flightlv acidu- 

 lated was applied as a mordant to another piece of kcrfey- 

 ttiere, and by immerfion in tincture of cochineal a dark. 

 mordorc colour was obtained. 



E\p. X. The fame was repeated with alkaline arfeniate of 

 -foda : an agreeable lilac \\as obtained. 



Exp. XI. Common white arfenic diffolved in water, gave 

 & lilac colour fomewhat dark. 



Though the author intended only to try the aftion of the 

 metals lately difcovercd on the colouring matter of cochineal, 

 refults before obtained from lead induced him to fubjeft this 

 metal alfo to fome new trials. He undertook at the fame time 

 to afcertain how far the ufe of nitrate of tin is indifpenfably 

 »eceHary in dyeing common fcarlet, by endeavouring to fub-» 

 ftitute for that fait muriate of the fame metal. Thefe re- 

 fearches gave rife to the following experiments : 



E\p. XII. A folution of acetite of lead being poured into 

 tinfture of cochineal, a violet blue precipitate was formed. 

 A piece of kerfeymere prepared with acetite of lead was then 

 immerfed in the fame tindlure, and a very agreeable violet; 

 colour was obtained. 



E\p. XIII. A folution of fine Englifh tin in pure muriatic 

 acid was expofed for four weeks in an open vefTel to thejic- 

 tiyn of the air. A piece of kerfeymere being boiled in this 

 folution, and then immerfed in warm tincilure of cochineal, 

 it alfunied a bright fcarlet colour. 



This relult is the more remarkable, as it has hitherto been 

 believed that it was impoffible to dve fcarlet without a folu- 

 tion of tin in aqua-regia; and indeed the red obtained by 

 employing common muriate of tin inclines to violet. It ap- 

 pears, therefore, that the oxygen of the nitric acid brightens 

 the colour. As the fame ftate of oxidation may be communi- 

 cated to muriate of tin by expofure to the air as by nitric 

 acid, the expenfe occafioned by the ufe of this acid and 

 that of fal-anmioniac maybe fparcd by fubftituting muriatic 

 ^cid, which is much cheaper. 



E.\p. XIV. A piece of kerfeymere was boiled for three 

 minutes in a neutral folution of muriate of barytes, and then 

 ■immerfed in tinfture of cochineal. The (luif afTumed a dark 

 colour, which, after being waflied and dried, changed to an 

 agreeable violet. 



Exp XV. Nitrate of barytes employed as a mordant gave 

 a ponceau red exceedingly agreeable.' 



4ii/). XVI. Acetite of barytes tried for the fame purpofe, 



gave 



