— 129 — 



when evaporated on the water-bath should not leave more than 0,1 °/o of 

 residue, tests for oily impurities. 



!) Menthol melts betv/een 43,5 and 44,5°. 



Mustard Oil, Artific (Oleum Sinapis). Colourless or yellowish, 

 assuming a yellow colour on prolonged keeping; di 6 o 1,022 to 1,025*); 

 soluble in alcohol in any proportion; AllyHsothiocyanate content not less 

 than 97°/o 2 ). 



a ) The minimum limit of value is too high; it should be 1,020. 



2 ) The estimation is carried out under heat by the method proposed by M. Kuntze. 

 Comp. Report April 1908, 70. 



Peppermint Oil (Oleum Menthce piperitce). The essential oil of the 

 leaves and flowering tops of the branches of Mentha piperita, L. and of 

 closely-allied Ifen^a-species 1 ); colourless or pale yellowish; di 5 o 0,900 

 to 0,910; « D — 25 to — 30 O2 ); gives a clear solution with 5 parts of dilute 

 alcohol 3 ). 



*) The proviso which includes as official the oil of other Mentha species, provided 

 it possesses the properties required by the Pharmacopoeia, is very sound, for in practice 

 peppermint oil is prepared from various Mentha-species t and chemical analysis affords no 

 clue whether or not the oil is derived from Mentha piperita. 



2 ) The limits of value indicated above are normal, but deviations above or below the 

 limit may occur. 



3 ) Many peppermint oils resinify readily and in that condition they only give opalescing 

 solutions after a short time; the cause of this phenomenon is as yet not quite explained. 



In the case of peppermint an indication concerning the determination of the menthol- 

 content might have been given, as has been done for santalol under sandalwood. A good 

 peppermint oil should contain at least 50°/o total menthol. 



Rose Oil (Oleum Bosce). Pale yellow; d 30 o 0,849 to 0,863; « D faintly 

 to the left, — 1 to — 3 01 ); At 18 to 20° small crystals are separated out 

 from the oil, which ultimately cause the whole of the liquid to congeal. 

 The oil melts again when the temperature is raised. 



3 ) The rotation of rose oil is often above this limit; we have observed up to — 4° 20'. 



Rosemary Oil (Oleum Rosmarini). Colourless or faintly yellowish; 

 d 15 o 0,900 to 0,920; soluble in half its vol. of alcohol. 



Sandalwood Oil (Oleum Santali). Colourless or pale yellow; di 5 o 0,973 

 to 0,985; « D — 16 to — 20°; gives a clear solution at 20° with from 

 5 to 7 parts dilute alcohol; the solution must remain clear when more 

 dilute alcohol is added 1 ). Total santalol-content (C15H24O) not less 

 than 90°/ 2 ). 



x ) The possible occurrence of clouding does not necessarily indicate adulteration, but 

 may also be due to products of decomposition or resinification such as are formed when the 

 distillation is carried out in an unsuitable manner. The solubility of sandalwood oil is also 

 diminished by age and under the influence of light and air. 



*) The estimation of santalol is carried out in the customary manner by acetylation, but 

 the quantity of sodium acetate prescribed by the Pharmacopoeia (2 g. for every 5 g. oil and 

 acetic anhydride) has been calculated on a very liberal scale; one-half of it is quite sufficient, 

 and is, in fact, the proportion generally taken for the acetylation process; in many cases an 

 excess of sodium acetate may even be directly noxious. The time allowed for saponification 



9 



