102 



they are derived. The nature of the saturated side -chains C 6 H U and 

 C 6 H 13 , whether they be alicyclic or aliphatic, does not appear to have 

 any appreciable effect on the rotatory power. In benzylidene camphor 

 and its anologues, such as benzyl camphor, it must therefore be the 

 character of the unsaturated benzene nucleus which exerts its influence 

 on the rotatory power of the asymmetric molecule to which it is 

 attached. 



PharmacologicO'physiological notes. 



A paper by E. Sack 1 ) on odoriferous substances and olfactory 

 sensations, contains interesting information which we can only reproduce 

 here in a few words, as we are only in possession of a short report 

 on the subject. What is usually understood under the expression 

 odoriferous substances, is, chemical individuals which are employed 

 for perfuming objects of use. An exact scientific definition, such as 

 for example that of the idea "dye-stuff", cannot be given of the 

 idea "odoriferous substance". They might possibly be designated as 

 carbon compounds which under certain conditions, whereby a chemical 

 change is excluded, emit a definite characteristic odour. It has often been 

 attempted to group odoriferous substances, like colouring matters, to- 

 gether from certain chemical points of view [Rupe and Majewski 2 ), 

 Klimont 3 )], but when such a group is submitted to a more thorough 

 study, there are found, besides much which is lawful and regular, so 

 many irregularities and exceptions, that it is impossible to carry the 

 principle through. The relationship between the character of the 

 odoriferous substance and the chemical constitution is usually not very 

 easily recognisable, and is frequently of a very complex nature. Above 

 all, one should not be led away too easily by theoretical speculations, 

 as statements in literature on odour-emitting bodies are afterwards very 

 often found to be unreliable. This may possible in part be explained 

 by the fact that many people are unable to smell correctly, and partly 

 by this, that many bodies which are looked upon as chemically pure, 

 do not possess a pure odour. Occasionally again, odoriferous substances 

 in solid or concentrated form do not possess the characteristic odour 

 which they have when properly diluted. It also happens sometimes 

 that the odour of a body in concentrated form differs entirely from 

 that of the greatly diluted body, so much so, that they might be taken 

 for different bodies. It is well know that the strength of the odour 

 in many substances does not at all stand in simple relation to the 

 degree of concentration or dilution in which the substances occur. Even 



x ) Chem. Ztg. 29 (1905), 1298. 



2 ) Berl. Berichte 33 (1900), 3401. 



3 ) Klimont, The synthetic and isolated aromatics, p. 7. 



