Popular Science Monthly/Volume 10/February 1877/Sketch of Professor J. P. Cooke Jr.

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THE position occupied by this gentleman in American science is one of marked distinction as a successful original investigator, and also as an efficient reformer in the work of scientific education. He is known at home and abroad both by the extent and importance of his experimental researches, and by the high-toned and thorough-going character of his expository works on chemistry and physics. It is a fact of no little significance that, although Prof. Cooke had the advantage of a university training, he was self-taught in chemistry, as his collegiate culture afforded no special preparation for his chosen field of labor, while the impulse which started him in a scientific career came from popular lectures outside the university. Yet he has probably done more than any other man to give chemical science its proper status in the collegiate curriculum as a valuable disciplinary study entitled to a leading place in an effective system of liberal culture.

Josiah Parsons Cooke, Jr., was born in Boston, October 12, 1827, and is a descendant of Major Aaron Cooke, who emigrated from England in 1630, and became one of the first settlers of Dorchester, and afterward of Northampton, Massachusetts. His father, a lawyer, is still living, at the advanced age of ninety, the oldest member of the Suffolk Bar.

Young Cooke received his early education at the Boston Latin School, and entered Harvard College in 1844, where he graduated in 1848. After passing a year in Europe for the recovery of his health, he returned to the university in 1849, as Tutor in Mathematics. He was soon afterward appointed Instructor in Chemistry, and at the close of the following year he succeeded to the Erving Professorship of Chemistry and Mineralogy, which he has held ever since.

Prof. Cooke never had the advantages of a European education, or indeed of any systematic teaching in science. He acquired his taste for chemistry at the early lectures of the Lowell Institute, in Boston, given by the elder Silliman, and, with the apparatus he had collected in a little laboratory in his father's house while a boy, he began his first course of lectures at Cambridge. For several years preceding his appointment no regular instruction in chemistry had been given to the undergraduates, and he had, therefore, the whole labor of developing this department of the college from the beginning. Although scientific schools had been previously established, both at Cambridge and at New Haven, yet Prof. Cooke was probably the first to introduce into our American colleges the experimental method of teaching physical science. He was, at first, greatly hampered by the inflexible recitation system, then universal, and success was only gained after many trials; but Harvard College may now claim to offer its undergraduates as broad and thorough instruction in the various departments of chemistry, including mineralogy, as any similiar institution in the world. Like most American men of science, Prof. Cooke's first duty was to teach, and his time and energy have accordingly been chiefly spent in developing methods of science-teaching, in building laboratories, in making collections, and in providing the various means of scientific instruction.

In connection with his teaching Prof. Cooke has published the following books:

"Chemical Problems and Reactions, to accompany Stöckhardt's Elements of Chemistry," in 1857; "Elements of Chemical Physics," in 1860; "Principles of Chemical Philosophy," in 1869.

In a notice of the last book the London Chemical News says: "So far as our recollection goes, we do not think that there exists in any language a book on so difficult a subject as this, so carefully, clearly, and lucidly written;" and in noticing the same book the American Journal of Science says: "To Prof. Cooke, more than to any American, is due the credit of having made chemistry an exact and disciplinary study in our colleges."

Prof. Cooke has given many courses of popular lectures in different cities—Lowell, Worcester, Brooklyn, Baltimore, and Washington—besides five courses at the Lowell Institute in Boston. His course of lectures at the Brooklyn Institute, in 1860, was subsequently published under the title of "Religion and Chemistry; or, Proofs of God's Plan in the Atmosphere and its Elements" (1864). In these discourses he aimed to show that the argument for design is not invalidated by the theories of evolution.

A course of lectures on electricity at the Lowell Institute, Boston, in the winter of 1868-'69, was followed by the publication, in the Journal of the Franklin Institute, of a series of papers on the "Absolute System of Electrical Measurements" and on the "Theory of the Voltaic Battery." In the last he developed a new theory of electricity, which has also been embodied in the later editions of his "Chemical Philosophy." This theory, like that of Dufay, admits two electrical fluids; but it regards these as separable constituents of the ether of space. These ethereal fluids, more or less blended, form an atmosphere around every molecule held in place by the immense force of molecular attraction; and when, by the various causes of electrical disturbance, the electrical ethers become more or less isolated on the same or on different molecules the two tend to flow together with great rapidity in virtue of their wonderful elasticity. If we assume that this motion takes place in accordance with the well-known laws of the diffusion of gases, the theory gives a satisfactory explanation of all well-established electrical phenomena.

In the autumn of 1872 Prof. Cooke delivered an interesting and important course of lectures on the "New Chemistry," which was subsequently published in the "International Scientific Series." His volume is one of the best and most successful of these books, and has been very highly appreciated both in this country and abroad, having been translated into most of the languages of Europe.

Among Prof. Cooke's lesser scientific publications may be mentioned the following:

1. "On the Relation between the Atomic Weights of the Chemical Elements" ("Memoirs of the American Academy," vol. v., 1854).

It was first shown in this paper that when the elementary substances are classified in natural groups, their atomic weights and other physical qualities are related by regular differences.

2. "On Two New Crystalline Compounds of Zinc and Antimony, and on the Cause of the Variation of Composition observed in their Crystals" ("Memoirs of the American Academy," vol. v., 1855).

This investigation proved that the crystalline form of these compounds was preserved under very considerable variations of composition, and indicated that the excess of one or the other constituent depended not solely on the composition of the menstruum in which the crystals were formed, but also on the chemical force which determines the union of the elements in definite proportions. The subject was still further discussed in the following paper, published during a visit to England.

3. "Crystalline Form not necessarily an Indication of Definite Chemical Composition, or on the Possible Variations of Composition in a Mineral Species independent of the Phenomena of Isomorphism" (Philosophical Magazine for June, 1860).

4. "On the Dimorphism of Arsenic, Antimony, and Zinc" (American Journal of Science for March, 1861).

It was here proved that all three of these elements are capable of crystallizing in octahedrons of the regular system.

5. "On Octahedral Galena" (American Journal of Science for January, 1863).

In this it was shown that the octahedral cleavage in this singular variety of galena from Lebanon County, Pennsylvania, is merely an unusual development of a constant condition.

6. "Crystallographic Examination of the Hebron Childrenite, and Comparison of this Variety with the Childrenite of Tavistock" (American Journal of Science for September, 1863).

7. "Crystallographic Examination of the Acid Tartrates of Cæsia and Eubidia" (American Journal of Science for January, 1864).

8. "On the Projection of the Spectra of the Metals" (American Journal of Science for September, 1865).

9. "On the Construction of a Spectroscope with a Number of Prisms by which the Angle of Minimum Deviation for any Pay may be accurately measured" (American Journal of Science for November, 1865).

10. "On the Heat of Friction" ("Proceedings of the American Academy," 1865).

11. "On the Aqueous Lines of the Solar Spectrum" ("Proceedings of the American Academy," 1866).

By comparing observations with the spectroscope and the hygrometer, it was in this paper first shown that a large part of the air-lines in the solar spectrum are due to aqueous vapor.

12. "On Danalite, a New Mineral Species from the Granite of Rockport, Massachusetts" (American Journal of Science for July, 1866).

This is a well-marked species allied to Helvin, but containing zinc in place of manganese.

13. "On Cryophyllite, a New Mineral Species of the Mica Family, with Some Associated Minerals in the Granite of Rockport, Massachusetts" (American Journal of Science for March, 1867).

Besides establishing a new species, this paper shows that in the veins of the Rockport granite there are closely associated a unicilicate and a bisilicate mica, which are isomorphous with each other, a circumstance which renders probable the theory that the wide variations in the composition of the micas may result from an isomorphous mixture of two similar types.

14. "On Certain Lecture Experiments, and on a New Form of Endiometer" (American Journal of Science for September, 1867).

15. "A Method of determining the Amounts of Protoxide of Iron in Silicates not soluble in the Ordinary Mineral Acids" (American Journal of Science for November, 1867).

16. "Crystallographic Determination of Some American Chlorites" (American Journal of Science for September, 1867).

The paper gives some new measurements of angles, and shows that there are two crystallographic types of chlorites corresponding to the well-known types of micas. It is further shown that there is a variation of optical angles in the chlorites, even on the same specimens, like that observed with the micas, and the inference is drawn that the variation is due to a similar cause.

17. "Atomic Ratios" (American Journal of Science for May, 1869).

It was for the first time pointed out in this paper that what mineralogists have long called the oxygen ratio of a silicate is really the ratio between the atomicities of the acid and basic radicals in these salts.

18. "The Vermiculites—their Crystallographic and Chemical Relations to the Micas, together with a Discussion of the Cause of the Variation of the Optical Angle in these Minerals" ("Proceedings of the American Academy," 1873).

This monograph contains the chemical analyses and crystallographic

descriptions of several micaceous minerals which are here classified together, and shows that the variations of the optical angle in the micaceous species is due to the interfoliation of the different members of a made. It also points out the close relation between hexagonal and trimetric crystals by showing that a hexagonal form and structure may result from a similar macling of trimetric crystals the prismatic angle of which is 120°.

19. "Melanosiderite, a New Mineral Species from Mineral Hill, Delaware County, Pennsylvania" ("Proceedings of the American Academy," 1875).

20. "On Two New Varieties of Vermiculites, with a Revision of Other Members of this Group," published in connection with F. A. Gooch ("Proceedings of the American Academy," 1875).

21. "On a New Mode of manipulating Hydric Sulphide" ("Proceedings of the American Academy," 1876).

This in application of the soda-water fountain, by which hydric sulphide is dissolved in water under pressure, and the magnet readily applied in a concentrated form.

22. "On the Process of Reverse Filtering, and its Application to Large Masses of Material" ("Proceedings of the American Academy," 1876).

This enumeration occupies but a small space; but when it is considered that each paper only states the results of elaborate and protracted original and experimental investigation, where the unverified guesses and the trials that go for nothing do not appear, we can form some idea of the amount of labor involved in the quiet life of a true scientific man.

Prof. Cooke has also written various articles for encyclopædias and reviews, and published several addresses. His discourse on "Scientific Culture," delivered at the opening of the summer courses of instruction in chemistry, at Harvard University, July 7, 1875, printed in The Popular Science Monthly for September, 1875, and republished in London, was one of the ablest contributions to the literature of scientific education that have appeared in a long time. Prof. Cooke's life has been one of valuable scientific service, which has, moreover, met with wide and cordial appreciation. He has been honored by the membership of many learned societies in this country and in Europe, and was quite recently elected foreign honorary member of the Chemical Society of London.