— 7o — 



15° 2^° 



gravities of the essential oils, as is usually done, at y^, but at ^o* 

 This rule has induced us to determine for all essential oils included 

 in the Pharmacopoeia, the differences existing between the specific 



15° 25° 



gravities at ^5 and at ^, so as to form an opinion whether and in 

 how far the limits of value given in the Pharmacopoeia agree with 

 those obtained at 15 . We have here in several cases found more 

 or less considerable differences. For the purpose of a better review, 

 we have combined the results obtained in a tabulated form (p. 71). 

 The limits of value given in the American Pharmacopoeia, which do 

 not agree with ours, are printed in heavy type. These limits printed 

 thus cannot and should not in our opinion be accepted as such, for 

 they are inconsistent with the values fixed for 15 , and are conse- 

 quently incorrect. Differences of 1 in the third decimal figure have 

 been left out of account, as they lie within the limits of error. We 

 would still mention that the differences between the specific gravities 



. 150 25 



determined at ^ and at ^, as given by us, agree well on the whole 

 with those ascertained previously by Schreiner and Downer 1 ), and 

 also that the average value of these differences is the same as that 

 found by those authors, viz. 0,00064 per degree of temperature. 



Of alcohols, the American Pharmacopoeia recognises a strong 

 alcohol of 94,9 per cent, by volume (Alcohol), and a weak one of 

 48,9 per cent, by volume (Alcohol dilutum). In the following pages 

 the former is designated simply as "alcohol." 



Anise Oil {Oleum anisi). Colourless or faintly yellow: d25o 0,975 

 to 0,985!); a D25 o — 2 02 ); solidifying point not below — f— 1 5°; soluble 

 in an equal volume alcohol and in 5 vol. 90 per cent, alcohol. 



*) The upper limit of value should be 0,988, as otherwise especially the oils 

 richest in anethol, and consequently the most valuable anise oils, could not be used. 

 Comp. also the table (p. 71). 



2 ) This should read: up to — 2°. 



Benzaldehyde (Benzaldehydum). Colourless liquid, strongly refrac- 

 tive, with at least 85°/ pure benzaldehyde 1 ); d25© about 1,045; a Di°°J 

 boiling point 179 to 180 ; soluble in alcohol in every proportion; test 

 for absence of chlorinated products. 



*) According to the method of determination by means of neutral sodium 

 sulphite indicated by the Pharmacopoeia, we found it impossible to obtain even 

 approximately satisfactory results; for this reason, we greatly doubt the usefulness 

 of this method. 



Bitter Almond Oil {Oleum amygdalce amarcz). Colourless or 

 yellow; content of benzaldehyde at least 85%^; content of hydro- 

 cyanic acid between 2 and 4% 2 ); (W 1,045 to 1,060 3 ); «d + o° 4 ); 



*) Pharm. Archives 4 (1901), 165. Report April 1902, 80. 



