or Li7ien Cloths capalle of resisting Bleaching^ &c, 1 1 



• Exp. IV. If, in the disengagement of oxygen gas from 

 a mixture of black oxide of manganese and sulphuric acid, 

 tare be taken not to push the fire to incandescence, the 

 sahne residue is blackish j but with a violent heat it turn* 

 to a yellowish white. On dissolving tiiis residue you se- 

 parate from it, by washing, an oxide of a dark gray, which 

 acquires the consistence of paste on the filter when deprived 

 ui the aqueous vehicle. On mixing this gray paste-like 

 oxide with ever so small a quantity of water, thickened with 

 gum-dragon, and printing with it, you obtain marks of an 

 extremely dark gray, which dry very speedily. This grav 

 colour cannot be removed by water, though it niay not have 

 been steeped in an alkaline ley : it is so tenacious and unal- 

 terable, that it withstands not only the action of all the 

 acids of a certain strength, but likewise all the processes of 

 bleaching, as well as the most complicated fabrication of 

 printed stuffs, without attracting the colouring parts of any 

 dye whatever. 



Exp. V. Were it not for the apprehension of weaken- 

 ing a little the place where the stufis are marked, equal parts 

 ot a mixture of the above-mentioned gray paste and a nitro- 

 muriatic solution of tin, charged with one-fourth part of 

 the metal, and thickened with gum-dragon, might be em- 

 ployed with advantage. This colour is equally unalterable 

 with that of the preceding experiment, and it possesses the 

 additional advantage of attracting, by its oxide of tin satu- 

 rated with oxygen, the colouring parts of any dye whatever, 

 and turning to dark brown m dyeing with madder. I shall 

 observe on this occasion, that, by this madder-dye, the 

 colours of marks produced by oxide of manganese, satu- 

 rated with oxygen, turn to a dark brown approaching to 

 black, whereas in a state less oxygenated they assume shades 

 more or less different. However, in all thcr-e circumstance? 

 it is necessary that there should be as much metallic oxide 

 as possible, without which you obtain only light tints of 

 various other colours. 



Exp. VI. Seeing that many in^oiublc metallic oxides ne- 

 vertheless acquire the property of adiiering to stuffs by means 

 of acids, I resolved to try if the same was the case with the 

 precipitate of manganese saturated with oxygen. For this 

 purpose I dissolved one part of sulphate of nianganest; in six 

 parts of water; and afterwards proceeding with the precipi- 

 tation to the point of saturation with a caustic alkaline ley 

 composed of half a part of quicklime, four parts of water, 

 and one part of calcined potash of commerce, I obtained a 

 precipitate of a yellowish white. I then added to the whole 

 a^jucous masi a sufficient quantity of oxygenated nuiriaiic 

 3 alkaline 



