Notes on scientific research. 125 



thio-ethers, $c.) and likewise Henning's 1 ) theory of compound odours which is based 

 on the formula and the odour of (impure) carbon disulphide, are both untenable. 



The connection between constitution and odour are dealt with in a paper by 

 M. Guerbet 2 ). 



In research work on olfactology it is of importance to examine at any given 

 moment the condition of the observer's sense-organ. According to H. Zwaardemaker 3 ) 

 this is done best (1) by establishing the accessibility of the nose to the air in respir- 

 ation; (2) by testing the sensitiveness of the sense-organ. Whether the nasal cavities 

 are normal or not can be ascertained, as the author proved years ago 4 ), by breathing 

 quietly and briefly on a metal plate held below the nose. From the shape of the two 

 breathing-spots each subdivided by a hiatus conclusions may be drawn as to the 

 transmissibility of the air through the nose. The acuity of the smell-organ is measured 

 by means of the olfactometer, which contrivance we described as early as in 1904 5 ). 



By means of an improved type of olfactometer the author found the following 

 limit values for a normal olfactory organ, expressed in tube-lengths for a just 

 appreciable smell-sensation of the aqueous solutions:— concentrated solution of amyl 

 acetate, 0.17 cm.; cone. sol. of nitrobenzene,, 0.19 cm.; 0.08 per cent. sol. of terpineol, 

 0.23 cm.; cone. sol. of artificial musk (trinitroisobutyltoluene), 0.18 cm.; 0.11 percent, 

 sol. of (commercial) allyl alcohol, 0.26 cm.; 0.26 per cent; sol. of guaiacol, 0.20 cm.; 

 0.32 per cent. sol. of caproic acid, 0.15 cm.; 0.38 per cent. sol. of pyridine, 0.11 cm.; 

 cone. sol. of skatole, 0.28 cm. For obtaining a general notion of the sensitiveness 

 of the observer's nose, the nickel supply-cylinder may be replaced by a piece of new 

 indiarubber tubing 10 cm. long with an interior diameter of 8 mm. An olfactory organ 

 may be considered to be normal when its "minimum perceptibile 5 )" for new, unused, 

 vulcanised caoutchouc lies at about 1 cm. of the olfactometrical scale. 



A camera inodorata, in which olfactometric experiments may be carried out 

 regardless of any by-odours, has been devised by H. Zwaardemaker ). The camera 

 is a box with glass walls of a capacity of 400 litres, the roof and the bottom being 

 of aluminium. All wooden parts are equally covered with this metal which absorbs 

 odorous matter but slightly. The box is placed on high legs, and the experimenter 

 can pass his head from below through an opening that can be closed by a slide. The 

 space may be rendered inodorous in a short time by means of an uviol or preferably 

 a quartz lamp. But few odours are not destroyed by ultraviolet light. As the author 

 demonstrated, in 1913, in conjunction with Tempelaar 7 ), many odorous bodies are 

 extremely sensitive to light, i. a., many esters, acetone, chloroform, borneol, eucalyptole, 

 eugenol, citral, terpineol, vanillin, coumarin, butyl alcohol, pyridine, skatole. Some 

 odour of ozone which may, be present after the illumination disappears soon. 



An olfactometer is attached under the slide at the bottom of the box, by which 

 olfactometrical determinations can be made. By means of special contrivances, the 

 inner tube of the olfactometer can be readily freed from any adhering scent. The 

 observer must have closely-cropped hair and a quite scentless skin. If necessary, 

 the skin must be thickly powdered with talc, or covered with odourless vaseline. After 



*) Henning, Uer Geruch. Leipzig 1916. — 2 ) Journ: de Pharm. et Chim. VII. 22 (1920), 344. As per 

 Chem. Zerdrolhi. 1921, II. 414. — 2 ) Perfiim. Record 12 (1921), 308. — *) Die Physiologie des Geruehs, Leipzig 

 1895, p. 72. — °) Cf. Report October 1904, 104. — 8 ) Perfum. Record 12 (1921), 243. — 7 ) Cf. Report 

 October 1913, 126. 



