ADDENDA. 225 



ture thoroughly and filter through a dry filter. Dilute 50 cc of the 

 filtrate with 200 cc of water, acidify with 1 cc of 10 per cent hydro- 

 chloric acid, and treat with an excess of barium chlorid solution. 

 After standing overnight, the precipitate is separated, washed, 

 ignited, and weighed in the usual way. 



HEAVY METALS. 



Determine as given under Naphthol Yellow S, page 212. 

 ARSENIC (SEEKER AND SMITH'S METHOD). 



Treat 10 grams of dye in a Kjeldahl flask with 100 cc water and 

 10 cc concentrated nitric acid. Warm gently and finally boil until 

 all action has ceased. Transfer to a beaker, make alkaline with 

 ammonium hydroxid, and proceed from this point, as in the case of 

 the solution of Naphthol Yellow S, page 212, continuing from the 

 point at which sodium phosphate is added. 



ETHER EXTRACTIVES. 



Dissolve 3 grams of dye in 200 cc of water and extract with ether, 

 as directed under Naphthol Yellow S, page 214. 



SULPHATED ASH. 



Determine as given under Naphthol Yellow S, page 214. 



CALCIUM. 



Determine as given under Naphthol Yellow S, page 215. 



SULPHUR. 

 Determine as given under Naphthol Yellow S, page 215. 



NITROGEN. 



Determine as given under Light Green SF Yellowish, page 222. 



XVIII, ADDENDA. 

 ADDITIONAL EXAMINATION OF COAL-TAR DYES. 



Since the foregoing report was written the chemical examination of 

 the coal-tar dye specimens collected in the summer of 1907 has been 

 completed. This investigation shows that 7 of the Green Table num- 

 bers then reported were not on the market, although those furnishing 

 the specimens included them at the time that the samples were sup- 

 plied. These numbers are as follows: not physiologically examined, 



97291 Bull. 14712 15 



