1825.] Mr. Badams on a Scarlet Sub-chromate of Lead. 305 



chromate of lead, as I may now venture to call it, I took 60 grs. 

 of yellow chromate and ground them with 40 grains of oxide of 

 lead, adding small quantities of hot water from time to time : 

 they united mto a red sub-chromate. 



Uses. 



I have endeavoured at some length to clear up the theory of 

 the two chromates of lead, because one radical error of the 

 nature which Grouvelle has committed, leads to endless mistakes 

 and disappointments in the practical operations which are 

 founded upon it. I have before alluded to the advantageous use 

 of sub-chromate of lead in giving a permanent orange scarlet 

 upon cotton. The mode of its application to calico printing 

 will be obvious to all who know the principle upon which yellow 

 chromate of lead is made fast; and no intelligent calico printer 

 will need any further information from me, as his own practice 

 in fixing the yellow chromate, added to what has been here said 

 of the nature and preparation of the red sub-chromate will 

 readily suggest what is necessary. I shall only remark that 

 nitrate of lead and an alkahne solution of chromate of potash, 

 will give him the colour. He may accumulate, besides, some 

 insoluble salts of lead in the pores of the cloth to give stabiUty 

 to the tint, and may modify the operation by various means, but 

 in all cases the colours must be heightened at last, by passing 

 them through boiling water. 



Scarlet sub-chromate of lead is extremely beautiful when 

 ground up with oil, and possesses great body as a pigment. It 

 is not degraded in its hue, hke vermihon, by admixture with white 

 lead ; it mingles with other colours, and shows no signs, after a 

 long exposure, of any change by time. As a water colour I dare 

 not yet say that it has been tried sufficiently to authorise a posi- 

 tive declaration that it will not blacken, but several pieces of 

 cards and thin paper painted with it, and hung upon the walls 

 of inhabited houses, likely to influence the colour of salts of 

 lead, have not in some months perceptibly diminished in bright- 

 ness. Should a longer experience confirm the promise already 

 given, I shall be happy to make it known to artists, as they have 

 nothing equal in colour to red lead which they can trust in their 

 drawings for a month even, and no tint would be a more desira- 

 ble accession to the pallet, than a bright and permanent scarlet, 

 or scarlet orange. 



Neto Series, vol. ix. 



