DURABLE AND SUPERIOR LAKE. 217 



as to be quite opake and muddy. Pour off the water, and The water when 

 add another pint of frefh water to the root, agitating and tri- | Ulbld Wlth c ,°" 



« _ ° o lour is poured 



turating it in the manner before defcribed; and repeat the off and another 

 operation till the water comes off the foot very (lightly tinged. pi L t b ad ; ded ? and 

 About five pints of water, if well agitated and rubbed, will fore: 

 extract from the root nearly the whole of its colour; and if Five fucceffive 

 the refidual root be taken out of the bag and dried, it will be P* ms * xtra ^ al1 



° the colour, leav- 



found to weigh not more than five drachms, apothecaries i ng five drams of 



weight; its colour will be a kind of light nankeen, or cinna- fibre « 



mon, and it will have entirely loft the peculiar odour of the 



root, and only retain a faint woody fmell. 



The water loaded with the colouring matter, mud be put The coloured 



into an earthen or well-tinned copper, or, what is ftill better, y^,'^™ e 



a iilver veffei, (for the uie of iron mud be carefully avoided 



through the whole), and heated till it ju ft boils. It mud then 



be poured into a large earthen or porcelain bafon, and an ounce and oneoz. cF 



troy weight of alum tiiflblved in about a pint of boiling foft Jj™frfS2 



water, muff be poured into it, and fiirred until it is thoroughly water added ; 



mixed. About an ounce and a half of a falurated folution of 2 » oz, *° f °£ J * 



veg. allc. affordi 

 mild vegetable alkali (liould be gently poured in, ftirring the a precipitate of 



whole well all the time. A confiderable effervefcence will colour * 



take place, and an immediate precipitation of the colour. The 



whole (hould be fufFered to (land till cold ; and the clear yellow 



liquor may then be poured off from the red precipitate. A 



quart of boiling foft water mould again be poured on it, and 



well (lined. When cool, the colour may be feparated from Edulcoration, 



the liquor by filtration through paper in the ufual way ; and drying Ifford 



boiling water (hould be poured on it in the tiller, till it paffes hair" an oun« 



through of a light draw colour, and quite i'ree from any alka- of lake » 



line tade. The colour may now be gently dried ; and when 



quite dry, it will be found to weigh half an ounce ; juft a fourth 



part of the weight of (he madder employed. 



By anal yds, this colour po(Te(Tes rather more than 40 per which contains- 

 cent, of alumine. If lefs than an ounce of alum be employed JJJLine. 8 ° 

 with (wo ounces of madder, the colour will be rather deeper ; 

 but if lefs than three quarters of an ounce be ufed, the whole 

 of the colouring matter will not be combined with alumine. 

 On the whole, I confider the proportion of an ounce of alum 

 to two ounces of madder, as the bed. 



Procefs 2. If, when the folution of alum is added to the Procefs 2. 

 waler loaded with the colouring matter of the root, the whole ?T0 J {g J°^ 



be iuffered to cool 



