Easterfield arid Bee — Molecular Weight. 497 



Molecular weight in phenol solution : Calculated 

 (C 5 H 8 N0 5 ) 3 = 486 ; found = 450. 



The characters given by Skey for the karakin prepared by 

 the animal-charcoal method differ in two important respects 

 from those above described. The melting-point according to 

 Skey is 100 8 , and the substance contains no nitrogen. At 

 first sight it would therefore seem that the two substances 

 are not identical. From Skey's paper, however, it would 

 appear that the karakin was not recrystallized, and this would 

 account for the difference in the melting-points. The failure, 

 on the other hand, to detect nitrogen in organic substances has 

 occurred so often in the history of chemical research, more 

 particularly before the application of the metallic-sodium test 

 had become general, that the authors do not attach much 

 importance to this apparent discrepancy. They would add 

 that they have prepared karakin by Skey's method and found 

 it to contain nitrogen, and to have the same melting-point 

 as the compound already described. 



The expenses in connection with this investigation have 

 been defrayed by a grant from the Royal Society of London. 



Akt. XLVII. — Raotdt's Method for Molecular Weight Deter- 

 mination. 



By Professor Easteefield and James Bee, M.A. 



[Read before the Wellington Philosophical Society, 5th November, 1901.] 



The teaching of practical chemistry at the present day differs 

 greatly from the teaching in vogue twenty-five years ago. At 

 that time qualitative analysis only was, as a rule, taught to the 

 elementary student, and experimental proof of chemical theory 

 was either ignored or only practised in the lecture-room. 

 Nowadays, however, the teaching of qualitative analysis is 

 usually prefaced by a series of simple quantitative experi- 

 ments, performed by the students themselves, and designed to 

 illustrate modern chemical principles. Such an introduction 

 greatly facilitates the understanding of the science. 



So far as we are aware, no attempt has been made to teach 

 the practice of molecular-weight determination by Raoult's 

 method to the elementary student, it being generally supposed 

 that expensive apparatus is necessary for such determina- 

 tions. As a matter of fact, the experiment may be success- 

 fully carried out with the simplest of school apparatus, and 

 with a very small expenditure of time and material. 

 32 



