CYANOGEN CHLORIDE. 333 



10. CYANOGEN CHLORIDE. 



1. Cyanogen chloride was prepared in the form of a colourless, 

 dry and pure liquid ; its purity was proved by the determina- 

 tion of the chlorine contained in a given weight of the com- 

 pound. This done, several samples of it were weighed into 

 sealed phials ; the weight of these samples was approximately 

 2 grms.; being 1/946 grin., 24675 grins., 2-137 grms., and 

 so on. 



2. This cyanogen chloride was converted into carbonic acid 

 (in solution) and ammonium chloride 



CNC1 (liquid) + 2H 2 + water = C0 2 (in solution) + NH 4 C1 



(in solution). 



The heat disengaged during this transformation was measured 

 by the following method, which consists in treating the cyanogen 

 chloride with potash and hydrochloric acid successively. 



Preliminary operations. A solution of potash containing 

 about 1 equiv. (471 grms.) in 10 litres of liquid was introduced 

 into the calorimeter, a proportion of it being taken that 

 would represent rather more than 3 equiv. for 1 equiv. of 

 chloride (CNC1 = 61*5 grms.) ; i.e. about 1 litre of the alkaline 

 solution. 



The rate of cooling during an interval of ten minutes, 

 measured before the actual experiment, was found to be nil ; 

 which is explained by the fact that the temperature of the 

 liquid was 21*51, that of the enclosing vessel being 21 '31. 



The phial containing the cyanogen chloride is surrounded 

 with a thick platinum wire, wound into a spiral, so as to add 

 weight to the phial and form a system that will remain at the 

 bottom of the water whether the phial be full, empty, or giving 

 off gases. This system is placed in a dry glass tube, which is 

 surrounded with ice, a little thermometer and a piece of potash 

 being put by the side of the phial; then we wait until the 

 thermometer records a temperature as near zero as possible ; 

 0*5 for example. It is necessary to take the precaution of 

 cooling the phial beforehand, if we wish to be able to open it 

 afterwards without loss or projection, after its introduction into 

 the calorimeter, seeing that cyanogen chloride boils at 12, and 

 that it would be violently expelled if the point of the closed 

 phial were broken, in which it had been kept a liquid at a 

 temperature of 21, in virtue of its own pressure. 



First stage of the experiment. The phial having been thus 

 prepared beforehand, and kept in a cold dry tube (dry, in order 

 to prevent the condensation of moisture on the surface of the 

 phial), the calorimeter is made ready. We then take the 

 platinum spiral surrounding the phial, and plunge the whole, 



