Method to purify Lead for AJfaying. 1 1 



lowed up, may perhaps enable our dyers to give to cotton 

 all, or at leaft a number of the colours which at prefent can. 

 only be communicated to woollen. We allude to the ufe 

 of fifli oil and fheep's blood, both of which animal fubftances 

 are confidered as being indifpenfably neceffary to the fuccefs 

 of the operation. 



Mr. Vogler, an able German chemift, after long and fre- 

 quent trials to give to linen and cotton alafting black colour, 

 found that, to gain this end, it was previoufly neceffary to 

 dip the yarn or fluff into a lolution of glue in water, in fuch 

 proportion as to give to the water when warm, being tried 

 between the fingers, a fticky or glutinous confidence ; and 

 recommends that care be taken only to wring, not to wafh 

 out the glue-water, part of which muft be allowed to dry 

 upon the yarn. Profcfibr Beckmann has noticed fimilar cir- 

 cumftances. 



The inference, as has been obferved by M. Berthollet and 

 others, is, that to fucceed in giving fome particular fixed 

 colours to vegetable productions, it is neceffary that they be 

 previoufly animalifed, as it were, by the application of oil, 

 blood, glue, or other animal matter. 



III. Method of purifying Lead from Gold and Silver, fo as to 

 male it ft for the Purpofe of AJfaying. By P£T. J AC. 

 Hjelm. From the New Tranfaclions of the Royal Aca- 

 demy of Sciences at Stockholm. 



a 



'N many occafions, particularly in trying the finenefs of 

 gold, it is neceffary to employ lead free from the mixture of 

 any other metal. For fuch experiments, above all, one muft 

 not make ufe of lead which already contains gold or filver, 

 or both thefe metals, without knowing the quantity, which, 

 at all times, occafions difficulty and often uncertainty. In 

 its natural flate lead, for the moft part, is found fo mixed 



with 



