56 



SCIENCE 



[N. S. Vol. XXVI. No. 654 



rent in the magnetizing coil. To obtain such 

 a curve, a coil, wound on a thin rectangular 

 bobbin which could be slipped into the air 

 gap of the electromagnet, was connected to a 

 ballistic galvanometer. The deflections of the 

 galvanometer when the coil is quickly with- 

 drawn from the air gap being proportional to 

 f, the required curve can be obtained by using 

 such deflections and the corresponding mag- 

 netizing currents as coordinates. 



The curve obtained will depend on the 

 magnetic history of the ring. If the curve 

 is to be of any use, the initial condition of 

 the iron must be one that can be reproduced. 

 The ring may be entirely demagnetized ini- 

 tially or it may be in the condition in which 

 it is left when a certain fixed magnetizing 

 current has been passed through it. This 

 current should be large enough to magnetize 

 the core quite strongly. 



Another curve can be plotted showing the 

 relation between the magnetizing current and 

 the force on the conductor, the current in the 

 conductor and the length of the conductor 

 being constant. If these two curves be plotted 

 to the same axes, it will readily appear that 

 the force is proportional to the intensity of 

 the field. 



The results which I have obtained from 

 these curves for the ratio of the field to the 

 force show a larger variation than do the 

 ratios found in Tables I. and II., but with 

 ordinary care the ratio of corresponding 

 ordinates on the two curves will not vary 

 more than three per cent. This seems to be 

 about as great accuracy as may be expected 

 with the apparatus in this present form. The 

 larger part of the error is undoubtedly due to 

 the uncertain variations in the magnetic 

 field. 



The apparatus as here described was de- 

 signed for the use of students of general 

 physics. Its special advantage is the direct- 

 ness with which the force is obtained in terms 

 - of quantities already familiar to the student. 



e, a. poeteb 

 Sfbacuse Univeksity, 

 March 5, 1907 



QUOTATIONS 



THE NEW ENGLAND COLLEGE 



Some of the New England college presidents 

 are practically facing the question whether 

 they should not voluntarily limit the number 

 of their students. Within the last ten years, 

 Dartmouth, for example, has nearly doubled 

 in size — an increase due largely to the success 

 of its professional and technical departments. 

 President Hopkins of Williams favors the idea 

 of limitation in the smaller colleges ; and there 

 is much to be said for his view, provided that 

 the income of the corporation is sufficient to 

 support an efficient faculty. In colleges like 

 Amherst, Bowdoin, and Williams a first-class 

 education can now be had, even as at the large 

 universities. But there comes a point in the 

 development of a college when the increase in 

 students entails an expenditure out of propor- 

 tion to the gains by tuition fees. The number 

 of instructors has to be multiplied, and there 

 must be a greater outlay for lecture-rooms and 

 laboratories. Many of the smaller colleges 

 would be helped if the craze for mere numbers 

 could be checked. The energies of the pro- 

 fessors could then be concentrated on the in- 

 struction of their relatively small classes, they 

 could insist on a higher standard of scholar- 

 ship, and possibly make the B.A. mean as 

 much as a degree in technology. — The N. Y. 

 Evening Post. 



NOTES ON ORGANIC CEEMISTRY 



ANHYDROUS SULPHOCYANIC ACID 



Although numerous salts of sulphocyanic 

 (thiocyanic) acid, ITSCN', are known, and 

 some of them are of considerable technical 

 importance, the free acid has, hitherto, never 

 been obtained in a state of purity. Wohler 

 believed that he had prepared it and Liebig 

 stated that it decomposed with extreme ease. 

 In 1887 P. Klason distilled the aqueous acid 

 and passed the vapor over calcium chloride, 

 heated to 40°, the unabsorbed material was 

 condensed at a low temperature and was 

 thought to consist of the anhydrous sulpho- 

 cyanic acid, but A. Eosenheim and E. Levy' 

 have recently shown that although Klason's 



'JBer. d. chem. Ges., 40, 2166 (1907). 



