June 18, 1915] 



SCIENCE 



909 



is not suited for the determination of sulphur 

 in kerosene, since even a poor oil must not 

 contain more than a few tenths of one per cent, 

 of sulphur and only a small amount of the 

 oil can be used. Probably by tenths was in- 

 tended a few hundredths of one per cent. Of 

 course the simplest way for sulphur in kero- 

 sene is the lamp method that has been used by 

 the Standard Oil Company for many years. 

 But sulphur to thousandths of one per cent, in 

 any crude petroleum or in any of its products, 

 except perhaps the most volatile gasoline, may 

 be expeditiously determined by combustion in 

 oxygen and titration. This standard method 

 in use for years is not mentioned. 



Neither Texas, Ohio, nor other American 

 crudes, except those in California, contain any 

 large proportion of nitrogen compounds, and 

 these compounds so far as examined are not 

 of the pyradine series but, including Baku- 

 crude, they are derivatives of the hydroehino- 

 lines. 



However, those minor inaccuracies do not 

 detract from the usefulness that this book of- 

 fers to all workers in these broad fields. 



Charles F. Mabery 



THE ADOPTION OF THE MISSOURI SYSTEM 

 OF GBADING AT GOUCHEB COLLEGE 



At Goucher College the faculty has recently 

 adopted the " Missouri System " of grading. 

 It may be of interest to some who are contem- 

 plating the introduction of this system, or to 

 others interested in the theory and practise of 

 grading, to learn a few of the details of this 

 proposed application of the system. 



Four passing grades and two grades below 

 passing are defined. Grade C is to be assigned 

 to approximately the middle 50 per cent, of 

 each class. Grades A and B together are as- 

 signed to those above C, grade A being that of 

 approximately the uppermost 3 per cent, and 

 B that of about the other 22 per cent. In the 

 opposite direction, grade D is to be assigned, 

 in required courses, to approximately the 15 per 

 cent., and in other courses to about the 22 per 

 cent., just below C. Grade E is to indicate 

 incomplete work or unsatisfactory work that 

 can easily be made up, such as is customarily 



marked "conditioned." Grade F denotes fail- 

 ure to receive any credit for the course. 

 Grades E and F together are to be assigned, 

 according to the discretion of the instructor, 

 to approximately the lowest 10 per cent, in re- 

 quired courses, and to the lowest 3 per cent, in 

 other courses. 



These percentages are summarized as follows : 



It will be seen that grade A is intended to 

 mark work of unusually good quality which it 

 seemed desirable, in the absence of any other 

 system of " honors " in the college, to distin- 

 guish from that accomplished among so large 

 a group as the upper fourth. The difference in 

 the percentages of conditioned and failed (E 

 and F) in required and not-required courses, 

 is intended partly as a check upon entrance ; it 

 also takes into account the fact that under the 

 usual conditions of admission to colleges, there 

 should be a considerable elimination of the 

 poorest students during the first years of the 

 college course, when the proportion of required 

 courses is high. Moreover, this arrangement 

 recognizes that students are guided somewhat 

 in their choice of elections by the advice of 

 instructors and by their tendency to elect work 

 in subjects which experience has shown them 

 fitted to continue. 



Theoretically the elimination of the poorest 

 students in the required work early in the 

 curriculum would afl^ect slightly the sizes of all 

 the remaining groups in the advanced or elec- 

 tive courses, but in practise this effect would 

 probably not extend beyond the lowest passing 

 grade; hence grade D is enlarged in these 

 courses, while the middle and higher grades 

 are not altered. Whether this will result in 

 justice on the whole, can be determined only 

 after experience with the system. 



The size of the upper grades A and B is 

 not increased in the most advanced or major 

 courses, for the simple reason that to do so 

 would in effect be applying the standard of 



