Transmission of the Trypanosoma Evansi by Horse Flies. 163 



The temperature of solidification was determined by means of the 

 Le Chatelier pyrometer, and proved to be 450° C, or 5° lower than 

 that given by Carnelly and Williams.* 



Some tellurium prepared from this 26 kilos, to chemical purity also 

 gave 450° C. as the solidifying point. 



Commercial tellurium obtained from Germany proved to have the 

 same melting point and specific gravity as my own tellurium. 



I found the electrical resistance to be about 800 times that of copper. 

 The resistance, however, appears to be very greatly dependent on the 

 crystalline conditions. 



A rod cast and cooled quickly has a lower resistance than one that 

 has been cooled slowly. A current of a few amperes will quickly raise 

 the temperature of a rod 0'2 inch in diameter. In casting small rods 

 of tellurium, of say finch diameter, there is much contraction, and 

 partial separation takes place even after some hours. 



The thermo-electric power of tellurium appears to be great. 



It has been a source of great satisfaction to me, as a metallurgist, 

 to produce so large an amount of tellurium from a mineral in which it 

 existed only in minute traces. The amount of 57J lb. (26 kilos.) of 

 tellurium was derived from 187,019 lbs. of crude bismuth, which 

 resulted from the treatment of 831,168 lbs. of mineral. 



(i The Transmission of the Trypanosoma Evansi by Horse Flies, 

 and other Experiments pointing to the Probable Identity of 

 Surra of India and Xagana or Tsetse-fly Disease of Africa." 

 By Leonard Rogers, M.D., M.E.C.P., Indian Medical Service. 

 Communicated by Major D. Bruce, K.A.M.C., E.B.S. Ke- 

 ceived January 28, — Bead February 14, 1901. 



(Communicated to tlie Tsetse -fly Committee of the Koyal Society.) 



The close resemblance between surra of India and tsetse-fly disease 

 of Africa has long been known, while Koch, after having seen the 

 living Trypanosoma Evansi at Muktesar in India, and soon after 

 studied the parallel disease in German East Africa, pronounces them 

 to be the same, and in his ' Beiseberichte ' calls the disease seen in the 

 latter place " Surrakrankheit." The appearance of the report made to 

 the Tsetse-fly Committee of the Royal Society by Kanthack, Durham, 

 and Blanclford on their experimental investigation of the latter disease, 

 suggested to me to repeat some of their experiments in the case of 



* ' Chem. Soc. Journ.,' toI. 37, p. 125. 



