ivToVEMBER 10, 1922] 



SCIENCE 



547 



■average death rate is 12 per thousand, in a city 

 ■of 100,000 population there will be about 23 

 ■deaths in a week. If black and white balls in 

 indefinitely large numbers are distributed in 

 the ratio of 23 black to 99,977 white and 

 100,000 are drawn, the most probable number 

 ■of black balls is 23, but one time in four there 

 -\vill be more than 27. Thus the recorded death 

 rate for a week for a city of 100,000 will nor- 

 'mally fluctuate. If it is on the average 12, it 

 will in half the weeks be approximately either 

 •as large as 15 or as small as 9. 



If the death rate exceeds 15 in two consecu- 

 tive weeks then the chances are fifteen out of 

 sixteen that it is due to some cause such as an 

 ■epidemic. The conditions are obviously of 

 practical importance for physicians and health 

 •officers. The situation for death rates is nicely 

 illustrated by the illustration that has been 

 'used of the distribution of black and white 

 ^balls in an urn. If the population of the 

 ■country were 100,000,000 and the death rate 

 were 12 (as it should be, but is not), then 

 1,200,000 people would die during a year. 

 Among 100,000,000 black and white balls there 

 :are 1,200,000 black. But if we draw 100,000 

 (i. e., take a town of that ijopulation) there 

 ■will be a chance fluctuation as described above. 

 It is also the case that the balls are not com- 

 ipletely mixed, there being more black balls in 

 ■some part of the urn than others. In some 

 .places we shall draw a larger proportion of 

 *blaek balls. When there is a negro population 

 'or a tenement house population or a large pop- 

 ulation of very young or very old people, there 

 ■are relatively more black balls. There are tem- 

 .porarily more black balls in one place when 

 there is an epidemic or the like. In that case 

 'we have the analogy of the black balls attract- 

 dng one another. 



This paper has been written to explain the 

 ■■methods used to select the thousand leading 

 ■American men of science by votes. The psy- 

 -ehologists have been taken as an example; if 

 space and time permitted tables and curves 

 -might be given for the other sciences and a 

 study of the data might yield results of inter- 

 -est. Such treatment must, however, be post- 

 rfponed or left to others. The object of the 



present paper will be accomplished if it makes 

 clear that the scientific men have been selected 

 and placed in the order of merit for their work 

 by valid objective methods and that the meth- 

 ods used have wide application. In a subse- 

 quent paper the distribiition of the scientific 

 men will be considered with special reference 

 to the changes that have occurred in the course 

 of ten years. 



J. McKeen Cattell 

 The Psychological Corporation, 

 August 1, 1922 



THE AMERICAN CHEMICAL 

 SOCIETY 



(Continued ) 



DIVISION" or LEATHER CHEMISTRY 



John Artlun- Wilson, chairman 

 Arthur W. Thomas, secretary 

 The mechanism of unhairing : John Arthub 

 Wilson and Guido Daub. A series of detailed 

 studies -n'as made of the mechanism of the unhair- 

 ing of skins by means of the sweating process, 

 lime liquors and caustic sulfide liquors. Sections 

 of skin were examined under the microscope at 

 different stages. In liming and in sweating, the 

 first action on the skin itself is the hydrolysis of 

 the epithelial cells of the Malpighian layer of the 

 epidermis, once the cells are destroyed, the remain- 

 der of the epidermis, the hair and the sebaceous 

 and sudoriferous glands are completely separated 

 from the derma and can then be removed mechan- 

 ically. In the sulfide method, the alkali destroys 

 the corneous layer of the epidermis and the skin 

 appears to be freed from epidermal matters on its 

 surface long before the alkali has penetrated to 

 the depth of the hair bulbs. Where this method 

 has been employed, the hair bulbs are usually- 

 found intact in the finished leather. The paper is 

 illustrated with photomicrographs. 



Pancrcatin as an xmhairing agent: John 

 Arthur Wilson and Albert F. Gallun, Jr. 

 When calf skin is swollen in dilute caustic soda, 

 neutralized with sodium bicarbonate, and then 

 put into a suitable solution of panereatin at 25° 

 C. exposed to air, the hair is completely loosened 

 in 24 hours, but the action is not due to the 

 enzyme, since it is checked by covering the solu- 

 tions with a layer of toluene. At 40° a solution 

 of panereatin fails to cause a loosening of the 

 hair of fresh, skin because the corneous layer of 

 the epidermis is impermeable to the enzyme and 



