OKGANOMETALLIC BODIES. 



OBGAX< "METALLIC r."l>irs. 



ISO 



The lower members of this type potii this power to inch an 

 extant u to rentier them spontaneously inflammable in air. 



jiimxU belonging to the second of the above sub-types are pro- 

 duced by the direct combinations of the cacodyles with negative 

 element*, the oxide* are base* of comparatively feeble power, f lowly 

 combining with two additional equivalent* of oxygen to form acids. 

 Thus oxide of cacodyl by exposure to air slowly pannes into cacodylic 

 acid: 



/ C,H, 



n s C.H, 



A.J C.IIj + 0, = As/ O 



(o Jo 



Oxide of cicodyl. ' v ' 



Cacodylic acid. 



The chlorine, bromine, and iodine compound* of this type are 

 volatile neutral bodies, which may be regarded as the haloid units of 

 cacodyl. Heated in contact with bichloride of platinum, the chloride 

 of cacodyl presents an interesting reaction ; two equivalents of 

 hydrogen in the cacodyl become replaced by a biatoniic molecule of 

 platinum, producing chloride of cacoplatyl : 



+ Pin. 



Chloride of cacody 1. 



+ !HC1 



CUlotidc of cacoplutyl. 



Cacoplatyl forms a series of compounds analogous to those of 

 cacodyL 



The only compounds of the third form yet known belong to the 

 methylic group. Arsenious dioxymethide is a crystalline body of a 

 neutral character, soluble in water, alcohol, and ether ; unchanged by 

 exposure to air, but transformed by distillation with hydrate of potash 

 into areenious acid and oxide of cacodyl. 



jc.n, 



.' \ - { O 

 



= AsO, + 



[C.H. 

 As { C,H, 

 O 



Hydrochloric acid converts it into arscniovia dichlormethide 



Ar&enious dioxymethide. Arsenious dichlormethide. 



Hydrobromic and hydriodic acids produce a perfectly analogous 

 change, whilst sulphuretted hydrogen transforms it into arsenious 

 dUulphouiethide. The chlorine compound can also be formed by 

 heating arsenic trichlormethide to 122 K. 



Aif.C.H.J.Cl, = A(C,II,)C1, + C.HjCl 



Chloride of methyl. 



Arsenic trichlormethide. 



Arsenious dichlor. 

 methide. 



The chlorine, bromine, and iodine compounds are neutral bodies of 

 considerable stability ; the two former are liquid, the latter solid and 

 crystalline. By the action of chlorine or oxidising agents, they are 



R + 



B- 



transformcd into bodies of the form As 



H- 



H- 



IR- 



Sub-typo As 



R- 



H has only yet been explored in the methylic 



R- 

 IR- 



group. The oxygen compound constitutes anhydrous monomethyl- 

 anenic acid, a direct derivative from arsenious dioxymethide. 



4- SAgO 



Aricniotu dioxymethide. 



MonomcthyUncnlc add. 



This acid is bibaric, forming stable and well-defined crystallisable 

 alts, the formula) of which are represented by the general expression 



The chlorine compound is exceedingly unstable; it may however be 



formed at 14* K., but is transformed at 32* into arsenious chloride and 



chloride of uu-thyl. 



A. 



t 



a 



A.CI, 



Chloiicle of metliyl. 



Arsenic tetracblormethldo. 



Arsenic dioxydichlormethide in a somewhat more stable body formed 

 by the direct union of chlorine with arsenious dioxymethid 



A. O + 



Jo 



Artenions dioxymcthiJc. 



n, 



Arsenic dioxydichlormethide. 



Nevertheless even this compound readily decomposes with the evolu- 

 tion of chloride of methyl. 

 (R + 

 R + 

 In sub -type As-j R the oxygen compounds are feeble monobasic 



R- 

 lll- 

 acids, of which cocodylic acid may be regarded as the representative. 



fR + 

 They are derived from the bodies As< R+ by direct oxidation, as 



1 



already described. Cacodylic acid is remarkable for its stability, 



neither fuming nitric acid nor a mixture of sulphuric and chromic 

 acids attack it even at the boiling point, and it may be heated to 

 390 F. without alteration. Although it is soluble in water, and con- 

 tains upwards of 54 per cent, of arsenic, yet it is not in the least 

 poisonous. Several deoxidising agenta reduce cacodylio acid to the 

 arsenious, or even to the diatomic, form. Thus phosphorous acid 

 transforms it into cacodyl : 



2(AB(C t H 3 ) t O.) 

 Cacodylic acid. 



(PO S ) = 2A.(C,H,), 

 Cacodyl. 



JPO, 



Zinc also produces the same result. 

 The cacodylates have the formula 



A.(C,n s ) 1 1 ,MO. 



Sulphocacodylic acid has not yet been isolated, but its salts present 

 the same relation to those of cacodylic acid as salts of sulphur acids 

 generally bear to those of oxyacids. Their formula is 



fR + 

 R + 



AB{C,H S ),S 3 , MS. 



Sub-type As ! R + has hitherto been very little explored : so far as 



R- 

 U- 



it is known, however, its members bear so close a resemblance to their 

 analogues in the antimony series as to require no further notice. 



Tellurium, Seriti. The close relations of tellurium to sulphur and 

 selenium place the organotnetallic bodies of this series in the same posi- 

 tion with regard to the sulphides and selenides of the alcohol radicals, 

 :i* the antimony and arsenic series stand in relation to the correspond- 

 ing compounds of phosphorus and nitrogen. 



The following are the chief known compounds : 



Tellurium-methyl . 

 Tellurous dlmcthoxldc 



Te 



' T ' 



IV. 



c,n, 



Tellurous mcthoxychloride 

 Tcllurlumethyl . . . 



! * - - .T 

 C.H. 



a 



Te, 



Tellurout dlcthoxlde 



Te. 



Tc'.lurous dlcthochlorido . . 

 Tcllurlnmamyl . . . 



O 



O 



c.n. 

 ci 



Te, / ' n ' ' t 

 ( c io"n 



The compounds of the alcohol radicals with tellurium are volatile 



