216 ANNUAL OF SCIENTIFIC DISCOVERY. 



Half its volume of acid will be enough, and if but little color is given, 

 a second use of the acid is not needed ; but this should be tried on a 

 small portion in a test-tube for greater certainty ; the purification is 

 finished with peroxide of manganese, with which it is to be agitated, 

 and left in contact until the odor of sulphurous acid is removed. Re- 

 distillation is not required, in fact, is not necessary to the manufac- 

 turer, who has only to wash well the first product with water, and 

 purify as above. As an instance of what Prof. Gregory considers the 

 gross ignorance of persons pretending to manufacture such articles, 

 he refers to a sample examined by him of sp. gr. about 1.000, and 

 w r hich seemed to have the following origin. The maker obtained two 

 fluids from distillation ; not knowing that the heavy one was chloro- 

 form, he threw it away and put up the lighter, a mixture of pyrox- 

 ylic spirit, its original impurities, the chlorinated oils, and a mere trace 

 of chloroform, and labelled it pure chloroform. Almost pure from 

 chloroform, Dr. G. well says. London Chemical Gazette, May. 



TEST FOR THE PRESENCE OF CHLOROFORM IN THE HUMAN BODY. 



THE following is the description of a process and apparatus used for 

 detecting the presence of chloroform in a human body, communicated 

 to the London Lancet, by Dr. Snow. 



The case was one in which the individual was supposed to have 

 been murdered by means of chloroform. The blood, or portion of the 

 body to be examined, was placed in a flask, from which proceeded a 

 tube, made red-hot in part of its course. Another glass tube attached 

 to the extremity of the latter was moistened inside with a solution of 

 nitrate of silver, and terminated in a Wolfe's bottle, the interior of 

 which was moistened with the same solution. Heat being applied to 

 the flask by means of the chloride of calcium bath, the vapor given off 

 had to pass through the red-hot tube, and any chloroform which might 

 be present was decomposed ; the chlorine and hydrochloric acid gas, 

 being set free, were arrested in the next tube, where they formed a 

 white precipitate of chloride of silver. The nature of the precipitate 

 was also proved by cutting the tube with a file and introducing a drop 

 or two of nitric acid into one portion, and a solution of ammonia into 

 the other. In this way the presence of chloroform was detected in the 

 bodies of two kittens, killed by inhaling the vapor, on six successive 

 days after the death of the animals, although no precautions were 

 taken to protect the bodies from the air, and the quantity inhaled by 

 each kitten was less than one minim. The parts of the animals ex- 

 amined were the viscera of the chest and abdomen, the brains and 

 muscles. From all, clear evidences of the presence of chloroform were 

 obtained. 



Dr. Snow had also obtained a precipitate of chloride of silver by 

 operating on some portions of the muscles of a child's leg amputated 

 under the influence of chloroform. The process was one of such 

 delicacy, that he had been able clearly to detect the presence of the 

 hundredth part of a grain when dissolved in a thousand grains of 

 water. The only substances which can yield chloride of silver by 



