MARKING COLOUR FOR LINEN, &C. 



$11 



of fulphate of manganefe in fix parts of water, and precipi- Experiments 

 tated the metal by adding to the point of faturation a cauftic ** lxz tt ofmln- 

 alkaline ley, made with half a part of quick lime, four parts ganefe and 

 of water, and one part of calcined potalh of the (hops. The Nation of iron. 

 precipitate was yellowilh white. To the whole aqueous mafs 

 I then added a iufficient quantity of oxigenated muriatic alka- 

 line lev, until the precipitate was completely faturated with 

 oxigen, and its brown colour became no deeper. I afterwards 

 collected on a filtre the precipitate or brown oxide of manga- 

 nefe, where, by the drainage of its water, it became pafty. 

 This brown pafte, mixed with half its weight of the molt con- 

 centrated acetic acid no longer afforded any but a weak brown- 

 ifh made; it was the (ame with a fmall addition of one or the 

 other of the three ancient mineral acids in a ftate of folution. 

 I did not fucceed better by mixing one part of the fame brown 

 pafte with an equal quantity of the acetic folution of iron, 

 marking 20° of the areometer of the faltpetre makers and 

 thickened with gum adraganth. This acetic folution of iron 

 containing only the quantity of oxigen neceiTary for the folu- 

 tion of the metal ceafed by a fironger affinity, the excefs of 

 oxigen of the brown oxide of manganefe, which in its turn 

 became diflblved, and the mixture of the two metallic folution* 

 afforded a yellow reddifh very deep and tranfparent liquid, 

 which confirms the fact that a metal faturated with oxigen re- 

 quires lefs acid for its folution than if it were in an oppofite 

 ftate, and that being then furnilhed with an excefs of acid, the 

 folution faturated with oxigen can admit a portion of another 

 metal without becoming turbid. This mixed folution of the 

 two metals afforded me only a rufty yellow* which was dis- 

 charged by weak fulphuric acid completely, in fomewhat lefs 

 time than was required to take out a ruft fpot in a lefs oxigen- 

 ated ftate. In order to obtain from the mixture of thefe two 

 metallic iolutions an indelible marking colour, it is necedarv 

 that the marks mould be fteeped for feveral minutes in an oxi- t 



genated muriatic alkaline ley, to precipitate and faturate the 

 oxigen of the oxide of manganefe. By mixing half a part of 

 the brown pafte of manganefe to two parts of the folution -of 

 the two metals the new portion remains untouched and renders 

 the whole turbid. This turbid mixture left only a light brown- 

 i(h mark on piece goods, which. hud remained long in the di- 

 luted fulphuric acid* 



V2 B* 







