[ 436 ] 



LXX. Notices of the Ucsidts of the Labours of Continental 

 Chemists. By Messrs. W. Francis and H. Croft. 



[Continued from p. 372.] 

 The Cacodyl Series (continuation). 

 pROTOCHLORIDE of cacody],KdCI\ cannot be obtained 

 pure by distilling the oxide of cacodyl with hydrochloric acid ; 

 a basic salt is then formed. The best method is to distil hy- 

 drargochloride of cacodyloxide with hydrochloric acid ; the 

 product must be dried over lime and chloride of calcium, and 

 then distilled alone in a tube filled with carbonic acid : 



KdO+Hg^Cnl ^f§'' 



^'^'■' jHg'^CK 



Theliquid thusobtained is aethereal, colourless, does not solidify 

 at — 45° C, and is converted a little above 100° C. into a co- 

 lourless gas, which inflames in the air. The fluid itself, when 

 burnt, deposits metallic arsenic, or arsenious acid, accordingly 

 as the air has more or less access. In oxygen it explodes 

 violently when heated. When the air has but very slow ac- 

 cess to it, it deposits beautiful colourless crystals. In chlorine 

 it inflames and burns with deposition of carbon. Its smell is 

 extremely penetrating and stupifying. In greater quantities 

 it excites to such an extent the mucous membrane of the nose, 

 that it swells, and blood drops from the eyes. It does not dis- 

 solve in water, but imparts its odour to it. In ajther it is in- 

 soluble, but soluble in alcohol. Dilute nitric acid dissolves it 

 without decomposition, the concentrated acid causes explosion. 

 The chlorine is precipitated entirely by silver salts. Caustic 

 lime and baryta do not decompose it, except at a high tem- 

 perature. An alcoholic solution of potash forms chloride of 

 potassium, and an aethereal volatile substance containing no 

 chlorine (C'H'^As-?), easily soluble in water and alcohol. 

 Sulphuric and phosphoric acids separate the hydrochloric acid. 

 Formula C^ H'- As- CI-'; sp. gr. of vapour 4'*56 ; calculated 

 4-86. 



By passing dried hydrochloric acid gas into alkarsin, a hy- 

 drate of protochloride of cacodyl is formed ; it is a thick oily 

 fluid, which is decomposed by distillation. 



Protoiodide of Cacodyl, Kd I-. — Formed by the distillation 



of cacodyloxide with concentrated hydriodic acid ; in the re- 

 ceiver under the water there appears a yellowish oily liquid, 

 which by slow cooling forms beautiful rhomboidal laminae of 

 a yellow substance ; it is then cooled, and the iodide remaining 



