— ii9 — 



The percentage of hydroxyl-groups is calculated according to the 



formula 



ni ^ 0,000719 -V- 17 • ioo r V 



x = "/.OH = 79 l6 . s 7 " = 0.07645- 



0,000719 being the weight in g. of 1 cc. CH 4 at o° and 760 mm. 

 pressure, 16 the molecular weight in g. of CH 4 , 17 that of OH, 

 V the volume of the CH 4 separated off, reduced to o° and 760 mm. 

 pressure, and expressed in cc, S the weight in g. of the substance 

 to be examined. 



In the case of compounds containing water of crystallisation, it 

 is necessary to calculate the percentage of active hydrogen, as both 

 hydrogen atoms of the water enter in reaction with methyl magnesium 

 iodide. 



CH3.MgI-l-H.OH = CH 4 + Mg/ 



\0H 



A 

 CH 3 • Mgl + Mg< =CH 4 + Mgl 2 + MgO . 



\0H 



For calculating the percentage of active hydrogen, the formula 

 0/ __ V- 0,000719 • 100 V 



y = '° H = WTS = 0,00449 g- 



is employed. 



Although the magnesium organic compounds are attacked by the 

 oxygen of the air, these determinations can be carried out in an 

 atmosphere of air; at any rate, Zerewitinoff obtained no essentially 

 different results, when he filled up the apparatus before carrying out the 

 experiment with an indifferent gas (nitrogen or methane). 



If in the case of acids the results of this hydroxyl- determination 

 are combined with the results of the titration, all data are obtained 

 for the calculation of the basicity and atomicity of the acid in question. 



Whether Zerewitinoff 's process can also be employed for the 

 valuation of essential oils, in which frequently compounds containing 

 hydroxyl are met with, is a question which can only be solved by 

 further experiments. 



Linalool determination according to Boulez. On the occasion 

 of a discussion on the linalool-content of linaloe oils, Simmons 1 ) on 

 the one hand, and Parry and Bennett 2 ) on the other, advance their 

 views on the determination of linalool according to Boulez, which 

 we have discussed in detail in our last Report (page 120). 



Simmons, who himself has carried out several unsuccessful attempts 

 to determine linalool, commits in a check test of Boulez's method the 

 same error in the calculation as Boulez himself, and thereby also 

 obtains apparently very good results. Parry and Bennett, on the 



