kinds of changes in reference to their velocity; the physiologist is actively registering the time element in vital phenomena through the rate of nervous transmission, the rate of muscular contraction, the duration of optical and auditory impressions, etc.; and we cannot ignore the fact that all the great living theories of the present contain the time element as an essential part. Now, I cannot but ask whether one reason why chemistry has evolved no great dynamical theory, that the word affinity has disappeared from our books, that we go on accumulating facts in all directions but one, and fail to draw any large generalization which shall include them all, may not be just because we have made so little use of the fundamental concept, time. To expect to draw a theory of chemical phenomena from the study of electrical decompositions and of thermochemical data, or from even millions of the customary static chemical equations would be like hoping to learn the nature of gravitation by laboriously weighing every moving object on the earth's surface and recording the foot-pounds of energy given out when it fell. The simplest quantitative measure of gravity is, as every one knows, to determine it as the acceleration of a velocity; when we know the value of g we are forever relieved, in the problem of falling bodies, from the necessity of weighing heterogeneous objects at the earth's surface, for they will all experience the same acceleration! May there not be something like this grand simplification to be discovered for chemical changes also?

The study of the speed of reaction has but just begun; it is a line of work surrounded with unusual difficulties, but I confidently believe it contains a rich store of promise; all other means for measuring the energies of chemism seem to have been tried except this. Is it not therefore an encouraging fact that to us, the chemists of the nineteenth century, is left for exploration the fruitful field of the true dynamics of the atom, the discovery of a time rate for the attractions due to affinity? I like to think so, and let us hope that the Newton of Chemistry may come in our day and while we yet have voices to honor him.

6. Torbern Bergman. De Attractionibus Electivis, 1775. Also in the 3rd vol. of his Opuscula Torberini Bergman Physica at Chemica, 1783.

7. H. Debus. loc. cit.

8. Chas. Daubeny. Introduction to the Atomic Theory, 2nd ed., p. 55.

9.

10.

C. L. Berthollet. Essai de Statique Chimique, 1803.

Sir H. Davy. Phil. Trans., 1807. Ditto, 1826.

11. Wurtz Dict. loc. cit.

12. Amadeo Avogadro. Journal de Physique, lxxiii, p. 58.

13.

B. C. Brodie. Quar. Jour. Chem. Soc. iv, 194.

14. D. Mendelejeff. Zeitschrift fur Chemie, 1869, 405 and Annalen der Chemie, 8 suppl., 133.

15. Lothar Meyer. Ann. der Chem., 7 suppl., 356.

16. J. Newlands. Chem. News, x, 59-94.

17. Watts' Dict., vol. 1, p. 865.

18. A. W. Williamson. A Theory of Etherification. Quar. Jour. Chem. Soc. iv, 106.

19. J. B. Richter. Anfangsgrunde der Stockiometrie, Breslau, 1792. William Higgins. A comparative view of the Phlogistic and Antiphlogistic Theories, 1789.

20.

21.

22.

23.

Wurtz Dict., art. Affinite, p. 72.

F. Guthrie. Phil. Mag. (4) xlix, 1-20. The first of several papers by him on Cryohydrates.

Thomas Andrews. Phil. Trans., 1844. Also Phil. Mag. xxxii, 392, followed by a series of papers on the same subject.

24. Thos. Wood. On the heat of Chemical Combination. The first of the series is in Phil. Mag. (4) ii, 268.

25. Favre and Silbermann. Ann. Ch. Phys. (3) xxxiv, 385 and in succeeding volumes.

26.

J. Thomsen. Pogg. Ann. lxxxviii, 349, and in following volumes. 27. Alex. Naumann. Lehr- and Handbuch der Thermochemie, 1882.

28. H. St. Claire Deville. Compt. rend. xlv, 857. Also in the Leçons de Chimie of the Paris Chemical Society, on Dissociation, 1864; and on Affinity, 1867.

.

29. Wurtz Dict. loc. cit.

30. Gladstone and Tribe. A law in chemical dynamics. Proc. Roy.

Soc. xix, 498.

31. R. B. Warder. Suggestions for computing the speed of chemical reactions. Proc. A. A. A. S., xxxii, 156.

32. J. H. Gladstone. Chemical Affinity as existing among substances in solution. Phil. Trans., March, 1854.

33. J. W. Draper.

Chemical Action of Light, Jour. Frank. Inst., xix, 469, 1837. Also many others on the same subject in Phil. Mag. from 1842 to 1857.

34. H. E. Roscoe. Measurement of the Chemical Action of light. Proc. Roy. Soc., 1857, 326. Also in conjunction with Bunsen till 1862 Edm. Becquerel. Chemical rays which accompany Light. Compt. rend., xiii, 198, 1841.

35

PAPERS READ.

OPTICAL METHODS OF ESTIMATING SUGAR IN MILK. By Prof. H. W. WILEY, Agricultural Department, Washington, D. C.

[ABSTRACT.]

THE paper contains a review of the determination of specific rotary power of milk sugar and fixes this number at 52.5 (a), as the one nearest the true power. Extensive experiments are described with various reagents for precipitating the milk albumen in which it is shown that the commonly accepted method by basic lead acetate is wholly unreliable. It is further shown that perfectly reliable results can be obtained by using acid mercuric nitrate or mercuric iodide acidified with acetic acid. The paper also compares the results thus obtained with those reached by evaporating the milk to dryness and extracting sugar with aqueous alcohol. By numerous combustions with soda lime it is shown that the basic lead acetate does not remove all the albumen from milk, but that there is left in solution as much as .25 per cent of these bodies. Since they are all laevorotatory, the effect of their presence is to make the dextrorotatory power of the lactose appear too small.

Similar combustions show that while the mercury reagents do not remove all the albumen, yet they do so to such a degree as to reduce their disturbing effects to a minimum and render them negligible. The paper closes with directions, based upon the experiments given, for making optical analysis of sugar in milk which are both reliable and speedy. The complete paper is in vol. 6 No. 5, of the American Chemical Journal.

ON CHLORPROPIOLIC ACID AND CERTAIN SUBSTITUTED ACRYLIC AND PROPIONIC ACIDS. By Prof. C. F. MABERY, Case School of Science, Cleveland, Ohio.

[ABSTRACT.]

By treating chlorbromacrylic acid with baric hydrate under carefully regulated conditions, I find that the elements of hydrobromic