ANT
ANT
( <52 )
The same ore lias since been subjected to acareful analysis by Klaproth. e
1. 300 grs. separated as accurately as possi-ble from the oxide of iron with which it isnaturally mixed, were digested in cold aquaregia, composed of 5 parts muriatic acid and 1part nitric. The undissolved residue was againsubjected to the same process, after which whatremained undissolved was well washed in alco-hol and dried. Its weight was 51 grs. of which41 grs. burnt off with all the appearancesattending- the combustion of sulphur, leavingbehind 10 grs. which dissolved entirely in aquaregia.
2. The solutions were mixed together in aretort and mucli concentrated ; water beingthen added a copious precipitate fell down. Thesupernatant liquor was again concentrated, anda second precipitate was obtained as before bythe addition of water.
3. After separating the precipitate the fluidwas again concentrated, and appeared of agrass-green colour; ammonia was then addedin excess which threw down a brown oxide ofiron weighing after calcination 13.5 grs.
4. The ammoniacal solution was evaporatedto dryness, and the saline mass gently ignited ■,the residue which had the appearance of yel-lowish brown micaceous scales was digested inmuriatic acid, in which it entirely dissolved, llymeans of caustic potash a precipitate of anapple-green colour was obtained, which by cal-cination left behind 93.25 grs. of pure oxide ofnickel of a slate grey colour, indicating 70.75grs. of metallic nickel.
5. The precipitate N° 2, proved on examina-tion to be arseniate of antimony, but all attemptsat an accurate decomposition of it were fruit-less.
Thus foiled, M. Klaproth had recourse to thefollowing method. 200 grs. of the levigatedore were ignited with 600 grs. of nitre; themass was then lixiviated and well washed. Thelixivium on being slightly acidulated with nitricacid gave no precipitate, a proof that no anti-mony had been taken up. Lime water was thenadded and a voluminous precipitate of arseniateof lime fell down. This latter after beingwashed and dried was mixed with one-third ofits weight of charcoal and sublimed in a retort,and afforded 22 grs. of metallic arsenic.
The matter insoluble in the lixivium wasdigested in aqua regia in which it dissolved al-most entirely, and from this solution water
» Klapr. Ess. ii. 134.
threw down a precipitate weighing II 6 grs.equivalent to 89 grs. of metallic antimony.
Hence the constituent parts of this mineral,omitting the oxide ol iron which is consideredby RI. Klaproth as accidental, are
25.25 metallic nickel
47.75 - antimony
11.75 - arsenic
15.25 sulphur
100 .
§ 2. Chemical Properties.
Much difference of opinion has arisen withregard to the number and composition’of theoxyds of antimony. Thenard reckons as manyas six, Proust only two. According to thelatter chemist the lowest oxyd or suhoxi/d iscomposed of 81.5 metal to 18.5 oxygen or 22.7oxygen upon 100 of metal; and the highestoxyd or pero.ryd contains 77 metal to 23 oxy-gen ; or 29.87 oxygen upon 100 of metal
Pr. Berzelius reckons four oxyds of anti-mony, two of which have the characters ofacids. We have not the particulars of the ex-periments, but the following are stated as theresults : 1
The first or lowest oxyd is obtained by ex-posing antimony to the action of the positiveside of the voltaic pile. It is grey, and whenin contact with acids that do not themselvesimpart oxygen, part of the oxyd returns to themetallic state, and the rest passes to the Secondoxyd and dissolves.
The second oxyd is the base of emetic tartar,and most of the other antimonial salts. This iswhite and fusible.
The third oxyd is also white but infusible ata white heat. It possesses all the characters ofan acid, and is called by the author StibiousAcid. The white oxyd of antimony by nitreis in fact a salt composed of potash with anexcess of this stibious acid, and is decomposedby boiling water into a neutral soluble stibiateof potash, and an insoluble portion with stillgreater excess of acid. From this solublestibiate of potash professor Berzelius has formedmany other neutral stibiates.
The fourth oxyd is straw coloured and is anacid with higher oxydation than the former,and therefore has the name of Slibic Acid.At a high temperature it gives out oxygen andpasses to the state of Stibious Acid.
a Au. Chira. tqm. 83, p. 169.