274 Mr. Ellis on the Corrections for Latitude [May 18, 



matters, or to fluids taken from the human stomach post mortem, the 

 extracts obtained from such fluids almost invariably produce on frogs the 

 effects of digitaline. 



11. This is due partly to the fact that the action of digitaline is gene- 

 rally more rapid than that of the poisonous constituents of the extracts 

 themselves, hut principally to the circumstance that it was necessary to give 

 only small doses of the extracts containing digitaline, in order to get the 

 characteristic action. 



12. The method of dialysis fails in many cases to separate digitaline 

 from complex organic mixtures which contain it; and this method is 

 rarely of service in aiding the detection of this poison by the physiological 

 test. 



13. "When digitaline was administered to dogs in quantities little more 

 than sufficient to destroy life, the extracts derived from the matters vo- 

 mited by these animals, or from the fluids contained in their stomachs after 

 death (when vomiting was artificially prevented), were found in each of 

 those experiments to produce on frogs unmistakeably the effects charac- 

 teristic of the presence of one of the cardiac poisons. 



NOTE. Received 18th May, 1865. 



We have now to add to the list of " cardiac poisons " the Manganja, an 

 arrow-poison, brought from the Zambesi Expedition by Dr. Kirk. Our 

 attention was directed to this substance, which is the fruit of an Apocyna- 

 ceous plant, by Dr. Sharpey, who informed us of the results of experiments 

 he had made on its action ; and we owe to his kindness the opportunity of 

 confirming his observations by our own experiments. 



III. " On the Corrections for Latitude and Temperature in Baro- 

 metric Hypsometry, with an improved form of Laplace's formula." 

 By ALEXANDER J. ELLIS, F.R.S. Received May 11, 1865. 



Adopting the notation in Table I. (p. 284), and the data of M. Mathieu 

 (Annualre du Bureau des Longitudes, 1865, p. 321), Laplace's hypso- 

 metrical formula, after some easy transformations, becomes 



^ H 1 =[logB-log--00007.(M'-m').]x[500+A'+a'] 



I8336 (\ -L 15 926 Yl T 



.(1 *cos2L) < \ 6366198/J L t 

 = [log B log b -00007 . (M' m')] x [500+A' 

 36-764 



In the last term in (a), h r Hj represents the product of the three pre- 

 ceding factors, W . T' . G a ; and z is left for the present undetermined. 

 If y be the total increase of gravity in proceeding from the equator to the 



