CHEMISTRY. 



141 



cocoanut-oil. Reichert's method, " Fresemus's 

 Zeitschrift," 1879, p. 68, which consists in de- 

 termining the acidity of the distillate of soluble 

 fatty acids and water, obtained under constant 

 conditions, commended itself as the only one 

 of the three that is with any practical degree 

 of accuracy capable of distinguishing between 

 cocoanut-oil, in mixtures or alone, and pure 

 butter-fat. 



Dr. J. Traube has found the most important 

 methods that have been proposed for deter- 

 mining the amount of fusel- oil in brandies to 

 be defective. Such are the two colorimetric 

 methods, and Rose's method, which is based 

 upon the increase in volume of alcohol contain- 

 ing fusel. He proposes a capillarimetric meth- 

 od, by which so minute a proportion of fusel 

 as -5*3- per cent, may be detected. It depends 

 upon the fact that the height to which aqueous 

 solutions of organic bodies of one and the same 

 series ascend in capillary tubes often decreases 

 with the increasing molecular weight of the 

 dissolved body. Hence, a very small per cent- 

 age of fusel in brandies might be expected to 

 betray itself by a reduction of the capillary as- 

 cent. The capillarimetric method has the ad- 

 vantages over that of Rose, that it admits a 

 more speedy execution of the experiments, and 

 that the difference in the composition of the 

 fusels has less influence in it than in that; and 

 it is very much more delicate. 



Mr. William Crookes's method of chemical 

 fractionation as specially applied to the "rare 

 earths" erbja, holmia, thulia, terbia, yttria, 

 and ytterbia, consists in fixing upon some 

 chemical reaction in which there is the most 

 likelihood of a difference in the behavior of the 

 elements under treatment, and performing it 

 in an incomplete manner, so that only a cer- 

 tain fraction of the total bases present is sepa- 

 rated ; the object being to get part of the mate- 

 rial in the insoluble and the rest in the soluble 

 state. The operation must take place slowly. 

 Let us suppose that two earths are present, 

 nearly identical in chemical properties, but 

 differing by an almost imperceptible variation 

 in basicity. Add to the very dilute solution 

 dilute ammonia in such amount that it can only 

 precipitate half the bases present. On filtering 

 we have the earths divided into two parts, and 

 we can easily imagine that now there is a 

 slight difference in the basic value of the two 

 portions of earth ; the portion in solution be- 

 ing, by an almost imperceptible amount, more 

 basic than that which the ammonia has pre- 

 cipitated. This minute difference is made to 

 accumulate by a systematic process until it be- 

 comes perceptible by a chemical or physical 

 test. When the balance of affinities seems to 

 be established, and the earths appear in the 

 same proportion in the precipitate and the 

 solution, they are thrown down by ammonia, 

 and the precipitated earths are Avorked up by 

 some other process so as to alter the ratio be- 

 tween them, when the previous operation can 

 be again employed. 



M. H. Moissan has effected a probable isola- 

 tion of fluorine, by passing a strong Bunsen 

 pile-current through hydrofluoric acid which 

 has been cooled to a state of tranquil ebulli- 

 tion at 23. The addition of a little water or 

 fluorhydrate of fluoride of potassium is essen- 

 tial to secure conductivity. Decomposition 

 proceeds continuously, with the disengage- 

 ment of^ hydrogen at the negative pole, and at 

 the positive pole of a colorless gas in which 

 crystallized silicon burns in the cold with great 

 brilliancy, becoming fluoride of silicon. De- 

 ville's adamantine boron burns in the same 

 manner, but with more difficulty, becoming 

 fluoride of boron. Arsenic and antimony com- 

 bine with this gaseous body causing incandes- 

 cence. Sulphur takes fire in it, and iodine 

 combines with a pale flame, losing its color. 

 It decomposes cold water, producing ozone 

 and hydrofluoric acid. The metals are at- 

 tacked with much less energy. Organic bod- 

 ies are violently attacked. From these actions 

 and other test-experiments, the author is satis- 

 fied that the gas described is either fluorine or 

 a perfluoride of hydrogen. 



A process has been devised at Buxton, Eng- 

 land, for disposing of the sewage of the town 

 by precipitating it by means of a mineral 

 water derived from the lower coal forma- 

 tions of the vicinity. This water contains 1'2 

 grains of iron per gallon in the state of ferrous 

 carbonate, held in solution by carbonic acid. 

 On exposure to the air the carbonic acid es- 

 capes, and the iron, taking up more oxygen, 

 subsides in the state of ferric hydroxide in 

 combination with a considerable part of the or- 

 ganic impurities suspended and dissolved. The 

 results were very satisfactory. They showed a 

 large reduction in the free and albuminoid am- 

 monias ; and they supply additional proof that 

 mineral salts are fully capable of precipitating 

 dissolved organic impurities. 



Prof. Harvey W. Wiley has been engaged in 

 experiments on optical methods for determin- 

 ing milk-sugar, particularly with reference to 

 finding the best method of preparing the milk- 

 sugar for the polariscope, and to making a com- 

 parison of the numbers obtained by this instru- 

 merit with those given by the ordinary process 

 of extraction. The reagents found to con- 

 tribute to the best results were basic plumbic 

 ascetate, sp. gr. 1*97, in the proportion of Ice. 

 to 50 or 60cc. of milk ; acid mercuric nitrate, 

 Ice. ; and mercuric iodide with acetic acid. 



In Steffen's patented process for extracting 

 sugar from molasses, sirups, and the juices of 

 plants, enough lime is mixed with an aqueous 

 saccharine solution to form a lime-saturated 

 saccharine solution from which a calcareous 

 saccharate is precipitated. The percentage 

 of lime in the finished and perfect saccharate 

 is then reduced by mixing the hard, purified 

 saccharate with a saccharine liquid, whereat 

 the precipitated hydrate of lime is separated 

 by filtering. 



Edward Hart, of Lafayette College, uses, in 



