M. Kuhlmann on Salts of Thallium, 525 



In this way a specimen of the graphite from the iron used in 

 a previous experiment was found to contain a quantity of nitrogen 

 equal to 0605 per cent, of the iron, which, with the quantity of 

 nitrogen found as ammonia, 0*103 per cent., makes 0*708 per 

 cent. 



The method of determining carbon in iron by dissolving it in 

 chloride of copper always gives too high results, because the 

 carbon, thus separated, contains nitrogen. If the quantity of 

 nitrogen in the graphite be added to the quantity of carbon 

 found by the chromic acid method, that is, 4*332 + 0*605, the 

 total, 4*937, is very near the quantity of carbon, namely 4*86, 

 found by means of chloride of copper. 



To determine the quantity of carbon in cast iron, Wich * adopts 

 the following method. He makes the iron the positive electrode 

 of a Bunsen's battery which is placed in hydrochloric acid, 

 the other electrode being platinum. When the current is too 

 strong, carburetted hydrogen is disengaged, and in that case 

 the current must be moderated by removing the platinum elec- 

 trode to a greater distance. In a few hours five to six grammes 

 of cast iron are dissolved, and the carbon remains and has the 

 original form of the metal. 



M. Kuhlmann, jun., has describedf several compounds of thal- 

 lium with organic acids. The starting-point for their preparation 

 was carbonate of thallium, which was prepared by adding baryta 

 water to a solution of sulphate of thallium until there was no 

 more precipitate. The liquid was then saturated with carbonic 

 acid, the excess of carbonic acid driven off, on which the carbo- 

 nate of thallium was obtained by slow evaporation in fine elon- 

 gated flat plates. 



The organic salts of thallium resemble potash or soda-salts, 

 excepting the ferro-, the ferricyanide, and the picrate. They 

 are mostly soluble in water, and crystallize easily. They are 

 generally anhydrous, and but little soluble in ether or in alcohol. 

 In analysing these salts various methods were adopted. The 

 cyanides were analysed by determining the nitrogen and hydro- 

 gen, and, in the sulphocyanide, the sulphur. 



The very soluble salts were changed into the chloride of thal- 

 lium by passing hydrochloric acid through the solutions. Another 

 method consisted in making use of the insolubility of platino- 

 chloride of thallium, Pt C1 2 T1 CI, which is more insoluble in water 

 than the potassium-salt. 



The author prepared the oxalate, C 4 T1 2 8 , and the acid oxalate, 



* Repertoire de Chimie, February 1862. 

 t Compies Rendus, October 13, 1862. 



