222 MM. De Luca and Ubaldini on Sulphur. 



being several times shaken with purified bisulphide of carbon. 

 When the sulphide was separated and filtered, it was evapo- 

 rated in the water-bath, and the sulphur weighed after being 

 previously dried and melted. 



The volume of the solution, the amount of agitation, the 

 temperature of the liquid, the light, contact, time, excess of 

 one or the other constituent, all exert great influence on the 

 final result of this kind of experiment ; so that in some cases 

 about two equivalents of soluble sulphur are obtained, while in 

 others insoluble sulphur is separated in greatest proportion. 



In this reaction acids of the thionic series are formed; and 

 according to M. Berthelot the sulphur separated from penta- 

 thionic acid should be the insoluble variety. Sulphurous acid 

 tends to increase the stability of insoluble sulphur ; and, accord- 

 ingly, with an excess of sulphurous acid the proportion of 

 insoluble sulphur is greater than when the substances used 

 are in equivalent proportions. 



A solution of common salt, shaken with the mixture of the 

 two solutions, precipitates the suspended sulphur and clarifies 

 the liquid. On subsequently oxidizing this liquid with chlorate 

 of potass and hydrochloric acid, the sulphur of the thionic acid 

 is changed into sulphuric acid, and may thus be determined. 



These researches show that the sulphur deposited by the 

 reciprocal action of sulphurous acid and sulphuretted hydrogen 

 consists of two varieties, one of which is soluble and the other 

 insoluble in bisulphide of carbon, the proportion between these 

 two varieties depending not only on the substances taken, but 

 also on the conditions under which the action takes place. The 

 experiments, finally, support the view that the atoms of which a 

 simple substance is constituted may unite at the moment of 

 separation and form complex molecules which prod ace all the 

 phenomena that can be realized with the ordinary compound 

 bodies to which we are accustomed to devote our attention 

 from this point of view. 



Wohler"* makes the following observation on the extraction 

 of thallium from a deposit from the sulphuric-acid manufactory 

 of Eingkuhl, where iron-pyrites are used. The substance is 

 exhausted with water acidulated with sulphuric acid, and the 

 thallium precipitated as chloride by means of hydrochloric acid. 

 The chloride is well washed with cold water, and converted into 

 sulphate by heating it with concentrated sulphuric acid. The 

 salt is dissolved in water and precipitated by zinc ; but, to avoid 

 the influence of the impurities usually present in zinc, the 



* Liebig's Annalen, May 1867. 



