196 REPORTS ON INVESTIGATIONS AND PROJECTS. 



hydrothermal equivalent had been established by burning known amounts of 

 pure cane sugar. Determinations of the carbon were made in most instances 

 as a check upon the purity of the specimens, using the method of Fries ; and 

 as many of the compounds contained an appreciable amovint of moisture, the 

 heat of combustion was determined on a water-free basis whenever it seemed 

 desirable. Descriptions of the method employed and of the 26 compounds 

 used are given in this paper, together with the heats of combustion found, 

 which are presented on the basis of constant pressure. The results represent 

 the average of two or more closely agreeing determinations. 



(9) A comparative study of temperature fluctuations in different parts of the human 

 body. Francis G. Benedict and Edgar P. Slack. Publication No. 155, Car- 

 negie Institution of Washington. 191 1. 



By means of modern apparatus and methods, it is possible to measure with 

 great accuracy the carbon-dioxide excretion, oxygen consumption, water 

 vaporization, and nitrogen excretion during any given experimental period, 

 as well as the heat eliminated by radiation, by conduction, and in the latent 

 heat of water vaporized. The measurement of the heat production, however, 

 is dependent upon an accurate measurement of the body temperature, and 

 this presents serious difficulties. In any method of measurement of the body 

 temperature thus far devised, it has been necessary to assume that the body 

 as a whole undergoes an average change in temperature equal to the fluctua- 

 tions shown by the measurement of the temperature in any one portion of 

 the body. This assumption, however, has been based upon evidence so uncer- 

 tain that a study of the simultaneous fluctuations in different parts of the 

 body was undertaken to obtain more definite information on the subject. 



In the research, the results of which are presented in this publication, a 

 study was made of the simultaneous fluctuations in body temperature with 

 reference to determining: (i) the best place for an accurate and constant 

 measurement of body temperature; (2) the temperature gradient of the 

 body; and especially (3) whether or not the temperature fluctuations occur- 

 ring in the different parts of the body are uniform. The thermal-junction 

 method was employed and a special apparatus was constructed, which con- 

 sisted of electrical measuring instruments, a thermal- junction system, and a 

 constant-temperature oven. Various forms of thermal- junction thermome- 

 ters were devised for the particular localities in which the temperature was 

 taken, and in order that small temperature fluctuations might be measured 

 with precision, the thermal- junction system also included a second series of 

 junctions which were placed in a constant-temperature oven. The apparatus 

 and method are described in detail in the report of the research. 



In the study made of the thermal gradient of the body, the rectum was used 

 with men and the rectum and the vagina with a woman. The measurements 

 were usually made with a double thermometer inserted at varying depths, 

 the results being presented in the form of curves. These indicate that the 

 thermal gradient between the surface of the body and a depth of about 5 cm. 

 is quite noticeable, but that it is safe to conclude that the temperature reaches 

 the maximum at a depth of 6 to 7 cm. 



In selecting the localities for the measurement of the body temperature, a 

 special study was made of temperature measurements in the mouth with both 

 clinical thermometers and thermal-junction thermometers. Two curves show 

 the results of these measurements. While no definite conclusions are drawn, 

 the experiments appear to show that temperature observations in the mouth 

 are liable to considerable error, and that in work requiring exact measure- 

 ments even the best clinical thermometers are unsatisfactory. 



