124 Prof. Arthur Smithells on the 



The arrangement used in the experiments to be described 

 is shown in the accompanying figure. Air under pressure is 

 led to a Goiiy sprayer (pulverisateur) at a and issues at c, 

 carrying with it a fine spray or dust of the salt solution con- 

 tained in b. The gas-supply by means of a tap at d can be 

 diverted to any desired degree through a " saturator " e, which 

 contains a roll of filter-paper or some asbestos moistened with 

 any volatile acid or other liquid whose vapour it may be 

 desired to add to the flame. The tube e is surrounded by a 

 jacket through which warm water or steam may be passed, to 

 aid in volatilizing the liquid in the saturator. The air and 

 gas pass by a T-tube into the cone separator, which consists of 

 two coaxial tubes connected by an india-rubber collar g and 

 maintained symmetrical by the brass guide h By adjusting 

 the supply of air and gas, the flame may be so arranged that, 

 the inner cone rests at h and the outer one at i. 



Flame- Spectra of Copper Compounds. 



In a previous part of this paper I have commented on the 

 difficulties of tracing the chemical processes which accompany 

 the production of flame-spectra. The difficulties are specially 

 great with salts of the alkalis, owing to the stability of their 

 compounds at high temperatures. The case of chloride of 

 copper, an easily altered substance, seemed likely to repay 

 study, and I now give an account of the results which have 

 been obtained. 



The spectrum produced by the introduction of cupric 

 chloride into a non-luminous flame was mapped by Bunsen 

 and Kirchhoff in their original memoir. 



In 1862 A. Mitscherlich, in a paper (Pogg. Ann. cxvi. 

 p. 499) which raised the question as to the distinctive character 

 of the spectra of compounds, described and mapped the 

 spectra corresponding to what he called copper, copper 

 chloride, and copper iodide. The copper spectrum was ob- 

 tained by using a solution of copper oxide in acetic acid ; 

 the copper-chloride spectrum by supplying a mixed solution 

 of copper chloride and ammonium chloride by means of a 

 Mitscherlich- tube to a Bun sen-burner. Mitscherlich also 

 noticed certain variations in the copper-chloride spectrum 

 according to the quantity of hydrochloric acid present, and 

 thought it probable that two spectra were obtainable, one of 

 cuprous and one of cupric chloride. 



In a later paper (Pogg. Ann. cxxi. p. 459, 1864) Mitscher- 

 lich described the spectra of copper compounds in greater 

 detail, and mapped carefully spectra which he attributed 



