368 



Dr. H. M. Vernon. Solubility of Air in [Apr. 1. 



air at 37° it is too viscid to allow the air bubbles to rise to the surface in a 

 reasonable time. Hence the solubility was determined at 45°. The lard was 

 heated to about 48°, and then shaken violently for a minute with air, its 

 temperature at the end of this time having fallen slightly below 45°. The 

 process was repeated, and after keeping the lard in a water bath at 45° for 

 about 35 minutes the gases were boiled off in the usual way. They came oft 

 quite as readily as from the olive and cod liver oils. The data obtained are 

 given in the table, they being calculated on the supposition that the specific 

 gravity of lard at 45°, as compared with water at 15°, is 0-895.* If the mean 

 values be compared with the mean values for the other fats, it will be seen 

 that the solubility of oxygen is practically constant throughout. That of 

 nitrogen varies slightly, it being 5*23 c.c. for olive oil (an average of the 

 values at 15° and at 37°), 541 c.c. for lard, and 5*07 c.c. for cod liver oil. 

 Still these differences are almost within the limits of experimental error. In 

 the case of the lard, it is possible that the two minutes' shaking with air was not 

 quite sufficient for complete saturation, but more thorough shaking was not 

 possible, as it brought down a slight precipitate which prevented the rapid 

 clearing of the air bubbles. 





100 c.c. of lard at 45° C. contain — 



Mean. 





c.c. 

 2-23 

 5'05 

 0-12 



c.c. 



2-40 

 5*09 

 0-12 



c.c. 

 2-35 

 5'18 

 0-15 



c.c. 

 2*33 

 5-11 

 0-13 



Nitrogen 



C0 2 



In that fats of such very different composition as the three experimented 

 with dissolve practically the same amounts of oxygen and nitrogen, we are 

 fully justified in assuming that human fat would behave similarly. From the 

 physical and chemical constants collected in the accompanying table,f we see 

 that the melting point of human fat lies between those of cod liver oil and 

 lard, whilst its iodine value is 61*5 per cent., or about the same as that of 

 lard. In that cod liver oil has an iodine value of about 145 per cent., and 





Cod liver oil. 



Olive oil. 



Lard. 



Human fat. 



Solidifying point 

 Melting point ... 

 Specific gravity 

 Iodine value 



c to -10 c 



0-928 at 15°/ 15° 

 123 to 168 per cent. 



-6° (?) 



0-917 at 15 /15° 

 79 to 88 per cent. 



27° to 30° 



36° to 48° 



0-895 at 45°/15° 



50 to 70 per cent. 



15° 



17-5° 



0-903 at 25°/25° 



61'5 per cent. 



* Lewkowitsch, loc. cit., p. 564. 



t Lewkowitsch, loc. cit., pp. 454, 477, 562 and 564. 



