March, igo6.] 



KNOWLEDGE & SCIENTIFIC NEWS. 



381 



It is necessary in the first place to remove tin and 

 antimony, since they are only partially precipitated by 

 the ammoniacal reagents employed; arsenic and 

 phosphoric acids have also to be got rid of, since they 

 would cause complication in precipitating the heavy 

 metals, magnesium, &c. The solution to be examined 

 is, therefore, evaporated repeatedly with concentrated 

 nitric acid; this converts tin and antimony into the 

 insoluble metastannic and antimonic acids, in which 

 form they are easily removed. Phosphoric acid is 

 eliminated by the well-known tin method, and arsenic, 

 if present, is either vaporised away as methyl arsenate 

 (by distilling with methyl alcohol and hydrochloric 

 acid), or is rendered " harmless " by reduction to the 

 arsenious state. In order to bring about the latter 

 change the author employs a mixture of fuming 

 hydriodic acid and hydrazine chloride; the reduction by 

 hydriociic acid alone is limited and reversible, but the 

 hydrazine (by reconverting I into HI) renders it com- 

 plete. 



Silver is separated in the usual manner by h\'dro- 

 chloric acid and the solution (2), which may now con- 

 tain the remaining (common) metals — I^'e, Pb, Bi, Al, 

 Cr, Hg, Cu, IMn, Zn, Cd, Xi, Co, (As"'), Mg, Ba, Sr, 

 Ca, K and Na — is mixed with hydroxylamine hydro- 

 chloride and excess of ammonia; it is then heated in a 

 water-bath until the odour of ammonia nearly disap- 

 pears. In this way, aluminium, iron, chromium, 

 bismuth, and lead are precipitated as hydroxides, and 

 mercury as metal. [The addition of the hydroxylamine 

 in this case not only ensures the complete separation 

 of iron, whether it be present as ferrous or ferric, but 

 it also entirely pre\ents the separation of manganese, 

 which would otherwise partially fall out as brown 

 hydrated oxide when the ammoniacal solution is ex- 

 posed, to air. The copper is reduced to the cuprous 

 state, and mercury to metal; these reducing effects will 

 also be brought about by hydrazine if the latter has 

 been employed for the reduction of arsenic acid as men- 

 tioned above.] 



The precipitate (3) is dissolved in concentrated nitric 

 acid and mixed with excess of ammonia; in this way 

 the mercury is retained in solution as a complex salt, 

 mercuri-ammonium nitrate, and the other metals (Fe, 

 Pb, Bi, Al, Cr), arc again precipitated. The latter are 

 separated and identified in the usual manner; the 

 bismuth as oxychloride, lead as sulphate, iron and 

 aluminium as hydroxides, and chromium as chromate. 

 For the oxidation of chromium in alkaline solution the 

 author employs potassium percarbonate, which not only 

 keeps better thim hydrogen dioxide, but is also more 

 economical. 



From the amtnonia-hydrow iamine filtrate after 

 acidification (3) the copjX'r, which now exists as 

 complex cupro-ammonium sail, is precipitated as 

 sulphocyanate or as iodide (if the arsenic acid reduction 

 has been gone through the cuprous iodide will, of 

 course, separate on merely acidifying this solution); 

 ammonia and ammonium sulphide are then added, 

 which precipitates manganese, zinc, cadmium, nickel, 

 and cobalt as sulphides. These are dissolved in aqua 

 regia, the excess of acid removed, and the solution 

 mixed with soda and hydrogen dioxide, or, better, 

 potassium percarbonate. Zinc now remains in solu- 

 tion as zincate, and the remainder are precipitated as 

 Mii()(CMl)2, Co(OIl)3, Ni(011)3, or Ni(OH)2, and 

 Cd(OH)2. Percarbonate is here advantageous, since 

 the nickel comes down as dark brown nickelic 

 hydroxide, which is easily filtered and washed. The 

 further separation is conducted on the usu;d lines. 



The filtrate (10) from the ammonium sulphide 

 precipitate contains arsenic as sulpho-salt (unless 

 arsenic was initially removed), and the other metals — 

 magnesium, barium, strontium, calcium, potassium, 

 and sodium as chlorides, &c. ; on acidification with 

 hydrochloric acid the arsenic separates as sulphide, and 

 the solution is examined for the remaining metals in 

 the usual manner after destroying the excess of 

 ammonium salts. 



A glance at the subjoined table, which is an 

 abbreviated form of the one given by the author, may 

 serve to indicate the essential stages in this new 

 scheme of separation. 



Evaporiition with 



bolution (1) Fe. Pb. Bi. Al. Cr. Hg. Ag. Cu. Mn. Zn. Cd. Ni. 



Co. As. Mg. Ba. Sr. Ca. K. Na. ' 

 Removal of phosphoric acid. Removal or reduction of 

 arsenic acid. Addition of hydrochloric acid. 



:ipitate (2) ,,,,"" 



Addition of hydroxylain 

 \g, ammonia. 



Solution (2) 



hydrochloride, and excess of 



Precipitate (3). 

 Fe. Pb. Bi. Al. Cr. Hg. 

 Dissolution in excess of n 

 acid and precipitation 

 ammonia. 



Solution (3). 

 Cu. Mn. Zn. Cd. Ni. Co. (Af). Mb. Ba. Sr. Ca. 



K. Na. 



Acidification with dilute hydrochloric acid 



and addition of ammonium sulphocyanate or 



iodide. 



Solution (9). 



.Addition of ammonia and 

 ammonium sulphide. 



So'ution (10). 

 (As). Mg. Ba. Sr. Ca. K. Na. 

 Acidification with dilute hydro- 

 chloric acid. 



Solution 



Separated by the 

 ordinary methods. 



Precipitate (il). 



Dissolution in hydrochloric acid 



and precipitation with ammonia 



and hydrogen dioxide. 



NoTK. — Residue (i) may also 

 contain Sulphaies of Pb. Ba. 

 Sr. Ca. It is examined in the 

 usual matiner. 



Solution (II). 



Cd. Ni. Co. 

 Evaporation with nitric acid to 

 destroy ammonium salts Dis- 

 solution in hydrochloric acid 

 (examination of a portion of 

 solution for Co by potassium 

 nitrite) addition of soda, potas- 

 sium cj-anide and ammonium 

 sulphide. 



Solution (t3). 



Ni. Co. 



Oxidation by air to 



coballicyanide and 



precipitation with 



Solution 

 (14). 

 Co. 



iHi-. l■^lilol^ of the Ocohuiicl M(Uia:.>HC (.Or. Henry Wood- 

 ward, F.R.S., and Dr. H. B. Woodward, F.R.S.) held a 

 reception on Tharsdav, February 8, to conimciiioiale the 

 publication of the 5oolh number of the magazine. The 

 rooms at No. 5, Johnson Street, Notling Hill Gate, W., 

 were well filled, and many ladies and distinguished men of 

 science gladly responded to the invitation. Excellent music, 

 vocal and instrumental, was provided, and geological photo- 

 graphs and drawings were exhibited. We trust the Gtohnii- 

 cal Magazine may long continue its most useful work. 



