September 13, 1907] 



SCIENCE 



345 



On the Separate Determination of Acetone 

 and Diacetic Acid in Diahetic Urines: Otto 



FOLIN. 



Measure 20-25 c.c. of acetone solution or 

 urine into an aerometer cylinder and add 

 0.2-0.3 gm. of oxalic acid or a few drops of 

 10-per-cent. phosphoric acid, 8-10 gm. of so- 

 dium chloride and a little petroleum. Connect 

 with the absorbing bottle (as in the ammonia 

 determination), in which has been placed water 

 and 40 per cent. KOH solution (about 10 c.c. 

 of the latter to 150 c.c. of the former) and an 

 excess of a standardized solution of iodine. 

 Connect the whole with a Chapman pump and 

 run the air current through for 20-25 minutes. 

 (The air current should be fairly strong, but 

 not as strong as for the ammonia determina- 

 tion.) Every trace of the acetone will now 

 have been converted into iodoform in the re- 

 ceiving bottle. Acidify the contents of the 

 latter by the addition of concentrated hydro- 

 chloric acid (10 c.c. for each 10 c.c. of the 

 strong alkali used) and titrate the excess of 

 the iodine, as in the Messinger-Huppert 

 method, with standardized thiosulphate solu- 

 tion and starch. 



The estimation of the acetone can be 

 made simultaneously with the determination 

 of the ammonia, by the use of the same air 

 current and even in the same sample of urine, 

 but the author does not recommend such simul- 

 taneous determinations except for cases where 

 the -amount of available urine is small. 



On Magnesium and Contractile Tissues: 



Percy G. Stiles. 



The author extended and confirmed the 

 findings of Meltzer and Auer. Magnesium 

 was found to have a direct inhibitory effect 

 on automatic tissue (plain and cardiac 

 muscle) and a depressing effect upon the 

 irritability of the non-automatic striped 

 muscle. This infiuence is slow to wear off 

 after the application, but seems generally to 

 favor the longer activity of the muscle — in 

 other words, it is conserving in character. 

 Magnesium appears to be the element to which 

 we may look with most reason when seeking 

 an agent that shall suspend katabolic changes 

 without permanently damaging living struc- 



tures. It is clearly less hurtful than potas- 

 sium in like concentration. Comparison of 

 magnesium with potassium shows that the 

 former is not so distinctly the antagonist of 

 calcium as is the latter. It also seems prob- 

 able that the power to mediate vagus inhibi- 

 tion, which Howell fixed upon potassium, is 

 a unique property of that element and not 

 shared by magnesium. 



On the Extracellular and Intracellular Venom 

 Activators, with Special Reference to 

 Lecithin, Fatty Acids and their Com- 

 pounds: HiDEYO NOGUCHI. 

 Calcium chloride stops venom hemolysis 

 caused in the presence of oleic acid or soluble 

 oleate soaps, but not that induced by lecithin. 

 In the majority of serums, including those of 

 man, horse, guinea-pig, rabbit, cat, rat, hen, 

 pigeon and goose, there exist greater or less 

 amounts of venom activators, and they can 

 be completely inactivated by calcium chloride. 

 Judging from the fact that lecithin in an 

 available form is not affected by this salt, it 

 is not likely that these serums owe their 

 venom activating property to lecithin. As 

 these activators are also extractable with 

 ether they probably are nothing else than cer- 

 tain fatty acids, and, probably, soluble soaps. 

 Dog's serum offers an exception to this, and 

 contains, besides fatty acids and soaps, also 

 activators of the nature of lecithin, for cal- 

 cium chloride fails to stop completely its 

 venom activating property. This lecithin-like 

 activator is not extractable with ether, but is 

 precipitable together with the serumgiobulin 

 by half saturation with ammonium sul- 

 phate. While the serum globulin falls out 

 as a precipitate during dialysis, this activator 

 remains in the solution, from which a large 

 percentage of lecithin is extractable with 

 warm alcohol. In many respects this ap- 

 pears to be a protein compound of lecithin 

 and possibly is identical with Chabrie's albu- 

 min, which seems to be absent from the ma- 

 jority of normal serums, which develops in any 

 serum heated to coagulation, and which rend- 

 ers all serums equally venom activating. 

 Ovovitellin is another form of protein com- 

 pound containing lecithin in available form 



