390 Mr. W. Coldridge on the Electrical and 



The effect of adding a drop of water to these crystals is to 

 produce stannic sulphide ; and this action is thus in harmony 

 with that described above of holding the drop of water in the 

 mixed vapours*. 



Judging, then, from the fact of the unaltered boiling-point of 

 the liquid, and from the analogy of SnCl 4 5H 2 S to SnCl 4 5H 2 0, 

 and from the fact that the former as well as the latter separates, 

 the conclusion that the sulphuretted hydrogen is merely 

 mechanically mixed with the chloride is strongly supported. 



Class B. The Effect of various Liquids on the Conductivity. 



I. Chloroform. — Chloroform was first taken because of the 

 similarity of its chemical structure to that of staunic chloride. 



The conductivity of chloroform was found likewise to be 

 nothing within the range of these experiments. The tetra- 

 chloride mixes perfectly with the chloroform. In the first 

 instance the proportions taken were two volumes of the former 

 to one of the latter. The conductivity of this mixture was 

 nothing. In the next experiment one volume of the tetra- 

 chloride was diluted with five of the chloroform. But there 

 was still no conductivity. 



In each instance the result was checked by placing a streak 

 of black-lead on paper in circuit instead of the mixture. 



There would seem a priori to be no chance of a reaction 

 between so stable and saturated a compound as chloroform 

 and stannic chloride ; as an experimental fact the mixture 

 does not conduct. The test was applied of passing in dry 

 sulphuretted hydrogen ; no precipitation of stannic sulphide 

 resulted; the behaviour was the same as if no chloroform had 

 been present, and in marked contrast to the influence of water 

 or absolute alcohol. 



II. Absolute Alcohol. — Eectified spirit of good quality was 

 dried by standing over lime and by subsequent distillation 

 from lime. The phenomenon observed on adding a drop of 

 this alcohol to stannic chloride is analogous to that which 

 occurs when water is added. A white beautifully crystalline 

 compound is formed and much heat is evolved. By adjusting 

 the quantity of alcohol and cooling the vessel with water the 

 whole of the liquid can be transformed into a mass of these 

 crystals, which dissolve again on adding more alcohol. This 

 alcoholate has probably the constitution SnCl 4 . 5C 2 H 5 OH, as 

 would be concluded from its analogy to the amyl alcoholate 

 described by Bauer and Klein (Zeits.f Chemie [2] iv. p. 370). 



* My best thanks are due to the authorities of Exeter Grammar School, 

 who placed their laboratories at my disposal during' the Christmas vaca- 

 tion, and to my friend Mr. J. M. Martin, who helped me in the manipu- 

 lation involved in the examination of the above change. 



