September 11, 18S5.J 



SCIENCE. 



211 



the subterranean part of the yucca the oil extracted 

 from the bark is solid at ordinary temperatures; from 

 the wood it is of a less solid consistency, while the 

 yellow base of the leaf contains an oil quite soft; and 

 in the green leaf the oil is still more fluid. Yuccal 

 was obtained from the bark and wood of the root. 

 It is a transparent ruby-colored substance, melts at 

 70° C, and its specific gravity is 1.091. A blood-red 

 color reaction was obtained by warming the resin 

 with ammonium molybdate, and a few drops of strong 

 nitric acid. Pyrophaeal was extracted from the yellow 

 base of the leaf, and melts at 79° C. The amount of 

 saponin obtained in the wood varied from 8.95 per 

 cent to 10.4 per cent. Saponin was also found in the 

 bark and leaves of the plant. 



Prof. F. P. Dunnington described a method of 

 fixing crayon drawings. The drawings made on un- 

 sized manila paper are saturated with a preparation 

 consisting of one part Damar varnish, and twenty-five 

 parts turpentine. After drying, they are ready for 

 use. A paper by the same author describes a pecul- 

 iar porous mineral containing titanic acid, found on 

 a steep mountain side, and evidently of igneous ori- 

 gin. The surrounding soil was found also to contain 

 titanic acid. The origin of the mass is somewhat 

 uncertain. 



Mr. O. C. Johnson presented a paper on negative 

 bonds, and a rule for balancing equations. After giv- 

 ing rules for determining bonds, the author presented 

 his views of simple oxidation, oxidation with combi- 

 nation, double oxidation and complex oxidation in 

 their relations to chemical equations. 



Mr. A. Y. E. Young presented a study of the ther- 

 mo-chemical reaction between potassic hydrate and 

 common alum. After describing tbe experiments 

 which had been made, the following conclusions 

 were reached : 1°. That if potassic hydrate in excess 

 be added to alum, there results a characteristic dis- 

 tribution of constituents between the soluble and 

 insoluble portions of the mixture. 2°. This distri- 

 bution is a function of temperature, as well as of 

 dilution and mass. 3°. This phenomenon is prob- 

 ably due to dissociation by water of compounds 

 AI2O3, and SO3, and of potassic alurainate. 



Prof. J. W. Langley read a paper on the results of 

 an investigation of the concentration produced by 

 the differential action of chemism on certain acid 

 radicles. The paper showed, that, by this action (as 

 for instance when a copper plate is suspended in so- 

 lution of argentic nitrate), the NO3 divided into two 

 parts, having an approximate ratio of 1:3. Copper 

 and zinc in aqueous bromine behave in the same 

 way. Copper in solution of ferric chloride, and zinc 

 in solution of copper sulphate, produce a concentra- 

 tion of the radicle in opposition to gravitation. 



By communication with the various members of 

 the section, the secretary had arranged the following 

 question for discussion: What is the best initiatory 

 work for students entering upon laboratory practice ? 



Dr. H. W. Wiley was requested to open the discus- 

 sion. He said it was with laboratory work largely 

 as Pope said about governments, ' What's best ad- 

 ministered is best.' Students beginning laboratory 



work should understand at once that chemical sci- 

 ence is no guess-work, but a science of definite pro- 

 portions. They should learn the use of the balance, 

 and their experimental work in general chemistiy 

 should be conducted quantitatively from the start. 

 Students should be taught to rely upon themselves : 

 their faculties of observation and powers of reason 

 should be developed. At first they should be kept as 

 much as possible from books, and from too garrulous 

 professors. They should be told nothing of the phys- 

 ical and chemical properties of a body, which, by 

 proper diligence, and under wise direction, they 

 might find out for themselves. For instance, in 

 studying hydrogen, the student should be directed to 

 take definite quantities of zinc and sulphuric acid, 

 to measure the volume of gas given off, to dry and 

 weigh the residual zinc sulphate, and study its prop- 

 erties, etc. Whether beginning students should be 

 kept at work in the study of general chemistry, or be 

 taught also analytical work, will depend largely 

 upon the judgment and taste of the instructor. 

 Laboratory work, in order to give its full benefit, 

 must be combined with lectures and recitations : and 

 through it all, the work illustrating stoichiometry 

 must be fully done and comprehended. The progress 

 of the work should be gauged neither for the dullest 

 nor brightest pupil, but the middle course will be 

 found best. In all cases, much will depend on the 

 judicious oversight and guidance of the instructor. 



Prof. K. B. Warder asked whether it were better 

 to begin with gases or with metals ? He was inclined 

 to prefer metals, since their properties were more 

 easily discovered. Prof. F. P. Dunnington suggested 

 a course of metallurgy and assaying as being well 

 adapted to a student's initial laboratory work; after- 

 wards the use of the blow-pipe could be introduced. 

 Mr. Thos. Antisell said that the object of instruction 

 ought to be considered in determining its character. 

 If the study of chemistry was begun only as a part of 

 a liberal education, the course of instruction should 

 be largely qualitative analytical work. On the other 

 hand, if the pupil was looking forward to chemistry 

 as a profession, it would be better to put him to 

 quantitative work. 



Prof. A. B. Prescott was impressed with the idea 

 that the study of chemistry might be approached in 

 two ways; viz., as descriptive chemistry, and, ex- 

 perimentally, in general chemistry. Students should, 

 in analytical work, practice first on known bodies 

 before beginning on unknowns. Care must be taken 

 not to place too much reliance on laboratory work 

 alone. It is of the utmost importance that rigid 

 class-work in the lecture and recitation rooms go 

 along with the experimental work in the laboratory. 

 As great a mistake may be made by relying on labo- 

 ratory work alone as there was formerly by neglect- 

 ing it altogether. 



Prof. C. F. Mabery regretted that chemistry was 

 not taught practically in high schools and academies. 

 School trustees generally thought that seventy-five 

 dollars a year was a liberal allowance for laboratory 

 purposes. He would have young people begin with 

 common phenomena, such as the rusting of iron, etc. 



