1906.] 



Chloroform in the Blood of Animals. 



423 



on any particular animal, which sometimes lasted two hours or longer, every 

 effort was made, by keeping a close watch on the animal, to prevent any 

 sudden fluctuations in the rate of administration — for instance, if the 

 animal held its breath the chloroform was not pushed. In no experiment 

 did the animal lose any blood beyond what was taken for the samples, 

 except in certain experiments deliberately undertaken to test the effect of 

 loss of blood. 



Mode of Estimating the Chlorine. — After careful consideration of the various 

 available methods for estimating chlorine, we selected, owing to the volatility 

 of chloroform, the well-known method of Carius, commonly used for the 

 determination of the amount of halogen in organic compounds. The 

 stoppered weighing tube, containing, as a rule, from 5 to 6 grammes of blood, 

 was placed along with 6 to 8 c.c. of fuming nitric acid (1*5), and an excess of 

 solid silver nitrate in a bomb tube, which was then sealed. The bomb was 

 then heated in the furnace to 150° C. for six hours. With the quantities of 

 material used, this time and this temperature proved quite sufficient to com- 

 pletely oxidise the organic matter. The bomb was then opened and the silver 

 chloride formed was weighed. It is generally considered that chlorine can be 

 estimated with great exactness by the gravimetric method, using paper filters 

 and, according to Fresenius, we can, with care, always obtain 99"9 to 100 - 1 for 

 100 parts of chlorine taken. By adopting Gooch's method of filtration and 

 J. P. Cooke's suggestion of washing with water containing a little silver 

 nitrate, by which the small minus error caused by the slight solubility of 

 silver chloride in water is obviated, and a few other simple precautions, a much 

 higher degree of accuracy can be attained. 



As the quantities of silver chloride weighed in our experiments were very 

 small — varying from O03 to 0'09 gramme — we thought it necessary to adopt 

 all possible precautions to obviate the slight errors, which, when large 

 quantities are weighed, are for ordinary practical purposes negligible. 



The contents of the bomb tube were transferred to a beaker, diluted with 

 water and heated to the boiling temperature for a few minutes. After cooling, 

 the liquid was filtered through the Gooch, and the silver chloride washed into 

 the crucible by means of hot water containing a little nitric acid and silver 

 nitrate. The washing was completed with cold water. The crucible and its 

 contents were then dried at 140° C. and weighed. The silver chloride was 

 then dissolved on the filter by means of strong ammonia, and the asbestos 

 washed with ammonia until free from silver. The crucible was then finally 

 washed with hot water, dried as before, and weighed. The difference between 

 the two weighings, (1) crucible + silver chloride + possible glass fragments and 

 (2) the crucible + fragments, gave the absolute amount of chloride present. 

 vol. lxxviii. — b. 2 K 



