Changes in Dielecty^io Constants and 171 Volumes. 67 



all ; the data are to be considered correct in all cases to and 

 including the second decimal place. Boiling the amyl alcohol 

 under reduced pressure diminished the air bubbles somewhat. 

 The best way to remove them seemed to be to roll the specific 

 gravity fiame round and round after displacing some of the 

 liquid with the proper quantity of solid. In this way a large 

 number of air bubbles were loosened and rose to the surface, 

 but not all ; for after the weighings were completed, another 

 rolling would show a few more air bubbles. In the worst 

 case, those remaining had a volume of perhaps (2™°^)^, hardly 

 more, so in this worst case the error due to *air bubbles fell 

 within the nncertainty due to variation in the temperature of 

 the thermostat. 



The solutes were purified carefully as in the earlier investi- 

 gations. 



The process consisted in saturating the kerosene or amyl- 

 alcohol with the solid whose density was to be determined, 

 finding the density of this saturated liquid in a specific flask 

 holding 25'^'^, and displacing some of the liquid by a known 

 weight of the solid as powder or small crystals. From 4 to 11 

 grams of solid were used. 



The weighings were not reduced to vacuo because the tem- 

 perature of the thermostat varied through a range of 0*2°. 



Two altogether independent determinations were made. 

 The temperature of the thermostat was 22*2°db0*l uncor. 

 The experiments were simple and need no detailed description. 



The data are given in the table below, the mean values 

 being used in the large table further on. L. and B. signify 

 Landolt and Bornstein's Tabellen. 



Weight in Grams of 1"==. 



Urea. 1-322 1-315 Mean = l-318 L.andB. 1-33 



Urethane 1-133 1-139 " 1-136 



Chloral hydrate 1-900 1-894 " 1-897 " 1-86 



Succimmid(C,H^02N) _ 1-408 1-406 " 1-407 



Acetamid 1-127* l-129f " 1-128 '^ 1-159 



Resorcinol 1-274 1-272 " 1-273 " 1-283 



Mannitol 1-486 1-480 " 1-483 " 1*488 



Benzamid 1-267 1-275 " 1-271 " 1-341 



^>Toluidin _ 1-122 1-124 " 1-123 " 1-046 



Acetanihd.., 1-204 1-207 " 1-205 " 1-211 



Naphthalene 1-169 1-176 " 1-172 " 1-145 



Acenaphthene 1-205 1-201 " 1-203]; 



Phenauthrene .... 1*179 1-181 " 1-180 



* Some crystals contained large bubbles. 

 f Fused and powdered. 



X Bubbles — (2"")' 



