METALS. 



77 



banted together, the melted selenium covers the surface 

 of the xinc, but does not combine with it. IT the 

 beat be increased much above the fusing point, the 

 former u voUtilixe.l, and the latter remain* covered 

 with a yellow pellicle. 



-n sine, at an elevated temperature, is introduc- 

 ed into the vapour of selenium, an explosion occurs, 

 and the vessel is lined with a lemon-coloured powdery 

 anbatance, which i< selenmret of r . > U soluble 



in nitric acid, with the disengagement of nitric oxide. 

 Sttenjurt! of' mercury. \\hcn selenium and mercury 

 are heated together, a substance resembling tin u 

 formed. If mercury be in excess, this is ex|>elled, 

 when the compound is subjected to heat ; the seleniu- 

 rct then sublime* without fusing, and condenses in the 

 form of white leaves, ha\ -allic lustre. SclenU 



uret of mercury i* not easily acted on by nitric acid. 

 When this is bailed an it, proto- seleniate of mercury is 

 farmed, end the nitric acid contains selenic acid. If 

 nranatic acid be unwed on the seleniate, selenium 

 precipitated 

 the mercury, 



I of mercury 

 r of tmtimemy baa a -*-i lustre and 



a be poured on tne seanuate, selenium u 

 ; the oxygen of the selenic acid pacing to 

 r. by which the red oxide is generated. 

 f mercury ia soluble in nitro-mamlic acid. 



' 



When arsenic is put into fused 

 *o metal* unite, and a black mass is 

 which, when heated to redness, boil*, and a 

 is formed, which appears to be per-st Icniurtt 



Platinum in powder, and ae- 

 ration of caloric, 



and leave* the platt- 



On this account the seleniate* act readily on a 

 im crucible. 



nurd of MoWrim is of a grey colour, and be- 

 fore the blow.ptpe emits part of the selenium. 



Srltmnrrl of oumaM has a silvery colour and metaU 

 Kc lustre, ana require* a red heat for its fusion. 



' '' tdturium it fusible, and sublime* in the 

 form of a metallic mat* H U also oxidated, and gene* 

 rate* seleniate of tellurium. 



Sdrxu Acid and Data. 



The affinity of selenic add for the base* seem* to be 

 below that at arsenic acid. The neutral 



mtmmmmMm n*n*n*n*n*mln%n> aW aviantea 1 r >_- | 



UJMIIUU.SJ iiiwiuirw, vr *|WIIWIT KHODtv in 



1mmmmm+1m+&mmmJl. m mmmmmmjmKm\ 



oxygen aa exist* in the base. The quantity of oxygen 

 in a base sunkient to saturate 100 of acid is 14.37. 



twoclaseeaof super-salts; the fret 

 add a* exists in the neutral 



of coan* than i* fee* tinea that quantity 

 of oxygen that the** is in the baa*. The*. *ah> Bene- 

 lius call* bi-aelcniate*. The other soper-salu appear t* 

 eaMtin four time* the aeid of the neutnl compound; 



Satanic acid form* alao *ab-aaha with the alkalies, 

 and with seaae of the metals. The alkaline teleusste* 

 have a saline taste. Thoae, with the earth* and the 



etals, posses* in 

 The ce 



by beat, w 

 tainmg foreign 

 curs when the 

 with charcoal. 



ta.teoftheb.se. 



ol wienie acid are decomposed 

 ** be wrasiooed by their con- 

 ile matter. The ame oo 

 of an alkali or earth is heated 



B acid and carbonic oxide are 



, and a small quantity of selenium sublime*. 

 when a metallic scleniate is treated in tin* w*y, the 



seleniate. 



selenium unites with the metal of the base, and form* a 

 seleniurt't. 



Selfiiate of poiassa is very soluble in water, and may 

 be obtained in small metalline grains by the evapora- 

 tion of the fluid. When evaporated to dryne&s, the 

 residue attracts moisture on exposure to the air. When 

 heated to redness it fuse*, and become* of a yellow co- 

 lour, but again assumes it* former appearance when it 

 cools. It i* insoluble in alcohol. 



Bi-teleJiiale of polatta i* deliquescent and soluble in 

 water, but erysttllises with difficulty. By the applica- 

 tion of long continued heat, half of the acid i* driven 

 off. This salt is sparingly soluble in alcohol. 



Q*aJii-teir*iate ofjtetatta cannot be obtained crystal 

 lised. It is very deliquescent. 



Lite of tody has the taste of borax. It is very 

 soluble in water, and afford*, on evaporation, small crys- 

 talline grains, which do not deliquesce. It i* not so- 

 luble in alcohol. By exposing this salt with muriate 

 of ammonia to a red heat, muriate of soda is left I n th is 

 way 100 of seleniate afforded 66] muriate of soda = to 

 35.5 soda. The salt is therefore composed of 

 64.5 acid 

 35.5 soda. 



7?i.*rl(*M*f of toda i* obtained in the crystalline *tte. 

 When heated, it undergoes fusion ; and if the beat be 

 strong, k part* with iu execs* of acid, and forms the 

 This ult is composed of 77 83 a. 



82.17 soda. 



of rxla crystallises in needhs. It 

 alter by exposure to" the air. 

 Sebmiole of fwtmomia is obtained in four-sided prisms, 



'leniatt of ammonia is obtained by exposing a so- 

 lution of the prKcdiag salt to the air ; and the 



QanaM ....:,-.-. :; i. i m Md 1-v ^V.^y 

 ctenk acid to a solution of tbo bi-aeloniate, or by eva- 

 porating the solution by heat 



Srltmiale of ammonia i* decomposetl by beat, water 

 and ammonia are Brat disengaged ; the aelcnic acid i* 

 then dscuSBBUssJ by the anummia. and selenium is U ft 

 in the retort. 



iait of time is sparingly soluble ; when heated in 

 a (Uas vessel it forms bubbles in the glus, and at last 

 perforate < 



IK-jriVuM/e i* formed by dissolving the above salt in 

 the acid. 



Seirnimlt afotryta U insoluble in water. It is coni- 



157.7 earth. 



.- formed by dissolving carbonate of 

 bas^la in selenic acid. It is soluble, and crystallizes. 

 It is composed of 100 acid and about 



68 baryta. 



liile qfilronlia is insoluble. 



The I'l-irlemirjie is sparingly soluble in water. By the 

 anplication of heat, the excess of acid is expelled. 



AeJswMife of magnttia it sparingly soluble. It at- 

 tacks glass in the same way aa the seleniate of lime. 



Seleniale of alumina is formed by adding bi-seleniate 

 of ammonia to muriate of alumina. It is decomposed 

 by heat giving out it* acid. 



liale nfginctHa is insoluble in w: 

 Meiuatt Iff tircoiia is also insoluble. 

 Proio-tfleniale of inm. Selenic acid acts with diffi- 

 cultv on iron. When a salt of iron containing the black 

 oxide is added to a solution of an alkaline scleniale, the 

 proto-seleniate of iron is precipitated. This salt is de- 

 composed by beat, and the oxide of the metal is re- 

 duced. 



