Chemistry and Physics. 75 



It will be observed that the difference between the heats of com- 

 bustion of two homologous and contiguous hydi*ocarbons is prac- 

 tically constant, being about 157 Calories ; while the corresponding 

 difference between the heats of formation is about 5*5 Calories. In 

 the methane series therefore the heats of combustion at constant 

 pressure are 213*5 + 15l'5n, in the ethylene series 341*2 + 157. 5n 

 and in the acetylene series 315*5 + \57'5?i ; the corresponding 

 heats of formation being respectively + 18*7 + 5*7^, — 14*6 + 5*5^, 

 and — 58*l+5*5?i. When a member of the acetylene series is 

 converted into the corresponding define, 43*3 Calories is set reef; 

 and the conversion of the olefine into the paraffin develops 39 

 Calories. The heat of combustion of trimethylene does not accord 

 with the hypothesis that it is a closed chain hydrocarbon. The 

 heat of formation of trimethylene dichloride, 4*3 Calories, shows 

 that the substitution of Cl a for H 2 produces a thermal disturbance 

 similar to that observed in the methane series. — C. B,., cxvi, 1333 ; 

 J. Chern. Soc, lxiv, ii, 444, Oct. 1893. G. f. b. 



6. On the Action of a Lcmolactic Ferment on Dextrose, 

 Rhamnose and Mannitol. — In the course of observations on the 

 nature of the micro-organisms which attack the ripe pear, Tate 

 succeeded in isolating one which produced marked laevolactic fer- 

 mentation of dextrose and mannitol. He has now studied this 

 fermentation and gives the following conclusions: The organism 

 which produces this laevolactic fermentation is anaerobic and is 

 characterized by forming two kinds of growth upon solid media 

 — a white growth of moist appearance consisting chiefly of rods 

 and cocci, and a tough, tapioca-like growth consisting of ascococci. 

 The fermentations brought about by this organism under aerobic 

 conditions in solutions of dextrose, mannitol and rhamnose are 

 fairly constant in character. From 9 molecules of dextrose 

 the organism produces alcohol 2 molecules, succinic acid 1, 

 lsevolactic acid 7 to 8 ; and acetic and formic acids in smaller 

 and variable proportions. If the organism has grown in 

 the ascoid form, the amount of lsevolactic acid is slightly less 

 probably from secondary changes. From 9 molecules of man- 

 nitol are obtained 6 of alcohol, 1 of acetic acid, 2 of formic acid and 

 12 of laevolactic acid, together with some succinic acid. From 

 9 molecules of rhamnose, 4 molecules of inactive lactic acid 

 and 5 of acetic acid are produced, alcohol being absent. This 

 cultivation in rhamnose solutions, producing inactive lactic 

 acid, does not cause the organism to use any of its activity in 

 causing lsevolactic fermentation of dextrose. The study of dex- 

 trose fermentations, in the opinion of the author, tends to indicate 

 that the attack of the organism is directed simultaneously against 

 nine or other multiple number of molecules — that is against a 

 group of molecules — rather than against single molecules. — J. 

 Ghem. Soc, lxiii, 1263, Oct. 1893. g. f. b. 



7. On Lead Tetracetate. — It has long been known that red 

 lead dissolves in hot glacial acetic acid yielding a colorless solu- 

 tion which on cooling deposits crystals. Hutchinson and Pol- 



