180 abstracts: chemistry 



and the one being compared, as well as the interchange of instruments 

 and observers between the stations, in order that there may be no uncer- 

 tainty from ignorance of the precise station difference, if any, due to 

 local attraction, either natural or an unsuspected artificial one. Speci- 

 mens of such intercomparisons are given in detail. 



The intercomparisons reported upon were made at the following obser- 

 vatories: Sitka, Alaska; Potsdam, Germany; Kew, England; Falmouth, 

 England; Pola, Austria; Toronto, Canada; Tiflis, Russia in Europe; 

 Tashkent, Russia in Asia; Baldwin, United States; Cheltenham, 

 United States; Zi-ka-wei, China; Dehra Dun, India; Helwan, Egypt; 

 Havana, Cuba; Hongkong, China; Honolulu, Hawaii; Vieques, Porto 

 Rico; Alibag, India; Apia, Samoa; Pilar, Argentine Republic; Sydney 

 and Melbourne, Australia; Christchurch, New Zealand. By means of 

 the results obtained by the Department at Kew and Potsdam further 

 intercomparisons of observatory standards are obtained indirectly 

 through the recent work of Dubinsky and Kiihl at additional observa- 

 tories as follows: Upsala, Sweden; Pavlovsk and Katharinenburg, 

 Russia in Europe; Rude Skov, Denmark; Irkutsk, Russia in Asia; 

 de Bilt, Netherlands; and Val Joyeux, France. The indirect compari- 

 sons are of especially great interest because of the conception given by 

 them of the relative precision obtainable with entirely different types 

 of instruments and independently determined constants. 



From a summary of the comparisons it appears that the provisional 

 standard adopted by the Department in declination is perhaps from 0.3 

 to 0.5 minute too high for east declination; in dip a corresponding amount 

 too low in northerly inclination; and in horizontal intensity as much as 

 0.0001H to 0.0002H too high. The probable errors of the determina- 

 tions are quite small, rarely exceeding 0.1 minute in declination, 0.3 

 minute in inclinations, and 0.00005H in horizontal intensity. The 

 uncertainties involved in reductions for diurnal variation are much larger 

 than the order of the probable errors but they may be considerably 

 reduced by suitably selecting the time for observation. J. A. F. 



CHEMISTRY.— A ssay of Lactic Acid. Elias Elvove, Hygienic 

 Laboratory, Public Health and Marine Hospital Service. American 

 Journal of Pharmacology, 83: 14-19. 1911. 



The United States Pharmacopoeia specifies a lactic acid containing 

 75 per cent of true lactic acid and having a specific gravity of 1.206 at 

 25° C. An acid of this specific gravity should contain about 85 per 

 cent of true lactic acid. This anomalous specification is due to the inac- 

 curacy of the pharmacopceial method of estimation, which involves 



