304 LEAD IN VARIOUS ARTIFICIAL PRODUCTS. 
colored by sulphuretted hydrogen. I succeeded in obtain- 
ing the lead in its metallic state from the incinerated matter. 
After this experiment 1 learned that the size was prepared 
in the environs of Lille, and that ceruse had been added to 
it ; fortunately, it was not of a nature to be employed as an 
alimentary substance. The communication, however, of 
this fact is interesting to manufacturers of woollen tissues, 
and with the view to be useful to them I thought it proper 
to give it all possible publicity. 
Some years ago I was asked by a laundress of Sevres 
(Madame P ) whence came the brown stains which 
appeared when she washed, for the first time, shirts, hand- 
kerchiefs, &c, made of cotton cloth. The loss which she 
suffered by several accidents of the kind induced her to find 
out the cause of them, and she discovered that these cloths 
came from one of the first manufactories in France, the Pa- 
risian agent of which was one of her customers. She sent 
to me a specimen of some new cloth, together with some of 
the alkaline matter, employed by her as ley, and which she 
obtained at La Villette. I recognised the presence of sul- 
phate of lead in the dressing of the cloth ; and, finally, 
having found that this alkaline matter was a mixture of 
highly-sulphuretted soda, potassa and lime, I no longer 
doubted that the stains were produced by a reaction of the 
alkaline sulphurets on the sulphate of lead contained in the 
dressing. Without entering here into the question, how 
far cloth, impregnated with sulphate of lead, may be in- 
jurious to health, we think that the process of giving body 
and firmness to cloth by mixing sulphate of lead with the 
dressing ought by all means to be prohibited ; and this is 
the more practicable, since, at present, for this purpose, in 
many establishments, sulphate of lime is employed without 
inconvenience. 
I will make some remarks with reference to the investi- 
gation of metallic matters in human and animal bodies. In 
speaking of the boiling of the Dutch company (Compagnie 
