286 CARNEGIE INSTITUTION OF WASHINGTON. 



was established with great precision. It was found that 29.4350 

 grams of sodium carbonate were equivalent to 59.9168 grams of 

 silver on the one hand and to 104.3212 grams of silver bromide on the 

 other. The values for the atomic weight of carbon calculated from 

 these data are almost identical, being respectively 12.000 and 12.001 

 if silver is taken as 107.87, or 12.005 and 12.006 if silver is taken as 

 107.88. It is needless to say that great care was taken at every step 

 of the work, and a special study was made of the neutralization of the 

 carbonates by means of indicators. It is not too much to say that 

 this investigation could not have been carried out under the unsatis- 

 factory conditions existing in Boylston Hall, so that the new labora- 

 tory has already begun to justify itself. 



(2) The atomic weight of sulphur: 



This investigation, carried on simultaneously with the preceding 

 by the same assistant, C. R. Hoover, was very similar to it. Sodium 

 carbonate prepared in the same way was exactly neutralized with 

 the purest sulphuric acid, and the solution was then evaporated with 

 the greatest care. The equivalence between the weight of the sodium 

 carbonate and sodium sulphate was thus established, 27.21565 grams 

 of the former substance yielding 36.47319 of the latter. On this 

 basis, if sodium is taken as 22.993 and carbon 12.005, sulphur is found 

 to be 32.059. Both these investigations were finished down to the 

 smallest detail, and it is hoped that they will soon be published. 



(3) Compressibility of organic compounds: 



With the help of Dr. J. W. Shipley, the investigation of the com- 

 pressibility of systematically related organic compounds was con- 

 tinued for the purpose of adding to the fullness of our knowledge 

 as to the relationships of various properties of material. Eighteen 

 substances were studied in detail, great pains having been taken to 

 purify the materials. Among these were not only a variety of the 

 simpler hydrocarbons, but also cyclohexane and cyclohexanol, from 

 which interesting data were secured. 



(4) Thermochemical research concerning organic compounds: 



This research, a continuation of work previously reported, was 

 taken up with the assistance of H. S. Davis. He made considerable 

 advance in the technique of the determination, especially with regard 

 to maintaining the temperature of the outside jacket like that within 

 the calorimeter. This was done by delivering the acid (which warms 

 the system by neutralizing the alkali in the environing jacket) from 

 a peculiarly shaped pipette planned to deliver at precisely the vary- 

 ing rate needed — as indicated by the known temperature-time curve 

 of the inner vessel. This device was found to facilitate greatly the 

 conduct of the experiment as well as to increase its precision. Much 

 time was spent also in studying the causes which prevent complete 



