# Popular Science Monthly/Volume 60/April 1902/Scientific Literature

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BIOGRAPHIES OF EMINENT CHEMISTS.
The literature of chemistry has recently been enriched by several biographies of chemists and by carefully edited works reproducing the letters that passed between certain chemists; the importance and value of these volumes is enhanced by the reflection that the history of the lives of the leading men in a growing science constitutes the most complete history of the science in that period during which they labored, and their lives and labors are reflected in their letters. These notions are appreciated by most of the editors of the correspondence we have in mind, and they make their tasks of double value by introducing numerous bibliographic and explanatory notes.
No student of the progress of chemistry in France during the second quarter of the century just closed can acquire a full and correct knowledge of the subject without a perusal of the life of Charles Gerhardt, edited by his son (bearing the same name), and by Edouard Grimaux (Paris, 1900). In his short life of only forty years, Gerhardt introduced ideas into chemistry that were at first thought to be revolutionary, but were eventually adopted even by his adversaries; his services to organic chemistry were of the highest importance; he first doubled the atomic weights of carbon, oxygen and sulfur, divided acids according to their basicity, and completely established the individuality of the equivalent, the atom and the molecule.
Of a very different type was his contemporary living across the Rhine, Schönbein, whose life has been sympathetically written by his successor in the University chair. Dr. Geo. W. A. Kahlbaum (Leipzig, 1899-1901,2 vols.). The painstaking, indefatigable discoverer of ozone, of gun-cotton, of collodion, and of the passive state of iron, forms a strong contrast to the brilliant, keen-sighted investigator in organic chemistry, Gerhardt. Schönbein's busy yet uneventful life reaped but a paltry reward for a discovery that subsequently brought the Swedish manufacturer a colossal fortune; but none knew better than Schönbein that the reward sought by the investigator in the chemical laboratory is success in wresting from nature her hidden truths.
Schönbein was a voluminous writer of letters; Dr. Kahlbaum made a collection of over 1,600, besides 350 printed papers, and analyzed them carefully in compiling the volumes named. One of his most regular and valued correspondents was Faraday, and the letters interchanged with him have been published in another volume edited by Dr. Kahlbaum and Francis V. Darbishire (Basle and London, 1899). These letters number 155 and cover the period from 1836 to 1862, beginning with a letter from Schönbein announcing the peculiar behavior of iron in nitric acid of a certain strength, and ending with a brief note from Faraday that painfully discloses his mental distress. The first mention of a 'phosphorus smell developed by electricity' occurs in a letter to Faraday dated April 4, 1840, and the exciting cause of this odor occupies some part of nearly every letter to Faraday during the succeeding twenty-two years.
Dr. Kahlbaum, with others, has published 'Twenty Letters,' exchanged by Schönbein and Berzelius in the years 1836 to 1847 (Basle, 1898), and the ​same in an English dress (London, 1900), also the 'Letters of Schönbein and Liebig, 1853-1869' (Leipzig, 1898), so that the correspondence of Schönbein is largely accessible to students seeking details.
These several volumes of correspondence suggest others that are analogous. The 'Letters of Berzelius and Liebig, 1831 to 1845,' edited by Justus Carrière with the cooperation of the Bavarian Academy of Sciences (Munich, 1893), and the correspondence between Berzelius and Wöhler, published by the Royal Academy of Göttingen, and edited by O. Wallach (Leipzig, 1901, 2 vols.).
And to complete this series of letters that passed between eminent chemists there remains the 'Correspondence of Liebig and Wöhler,' edited by A. W. von Hofmann, and Emilie Wöhler (Braunschweig, 1888, 2 vols). These cover the long period from 1829 to 1883. The inter-relations of these six works with the dates of the correspondence and of the death of each chemist, may be graphically shown by a diagram.
The perusal of letters between intimate friends having mutual interests in kindred studies is much like listening to conversation carried on between them; they reveal their daily life, domestic happiness and difficulties, their likes and dislikes, their humor and their satire, their successes and failures in research, and their ambitions and discouragements. They also disclose their weaknesses and perhaps their foibles, and they unconsciously divulge the greatness of their intellects, all in simple language, not written to produce startling effects nor to exaggerate their own importance in the minds of readers.
All these volumes are illustrated by one or more portraits, and some of them contain facsimiles of manuscripts.
MOSQUITOES.
A Monograph of the 'Culicidæ or Mosquitoes of the World' has just been prepared by Mr. Fred. V. Theobald, and is published by the British Museum as one of its regular series. There are two volumes of text aggregating 835 pages and one volume of plates, numbering 37 and containing 148 colored figures of adults. Then there are 5 plates, each containing six solar prints of microphotographs illustrating wing scales. In the text are 318 woodcuts, half-tones or similar figures. In these books 258 species of mosquitoes, divided among 22 genera, are described, and 37 species in 10 genera are credited to North America. Although the work is just off the press it is already out of date, and in the introductory remarks by the director of the museum, dated November, 1901, a supplementary volume is promised. All these facts indicate the remarkable interest that has been of late universally aroused in the subject, and the enormous collections that have been and are now being made in all parts of the world. In the United States several new species were recognized and described in 1901, two of them from New Jersey. The life history of several species has been made out, and good structural characters for their separation appear as the result of American study. Mr. Theobald describes 136 new species; almost as many as were described in all previous ​times, and he indicates the possession of something like 50 additional forms.
Almost 100 pages are devoted to the peculiarities of mosquitoes in all stages, and to the methods to be era-! ployed in studying them. The mouth: structures are explained in the conventional way and the matter of food is gone into somewhat in detail. Of course comparatively few mosquitoes ever get a meal of blood, and yet it would seem that for some species such a meal is an essential preliminary to reproduction. All sorts of vertebrates may be attacked, even fish and reptilia, and invertebrates seem almost as susceptible. The males, being unable to puncture either animal or vegetable tissue, are confined to a diet of prepared liquids—nectar and the like—but do not despise others, like beer and wine, when they can get them.
To mosquitoes as disease carriers only a few pages are devoted; the author referring to such writings as Ross's, Grassi's, Nuttall's and others. He specifically discusses 'Malaria,' filariasis and yellow fever, though adding nothing from personal observation. Birds and probably some animals suffer from diseases carried by these insects and usually only one, or a small group of species, acts in the transmission. Thus the species of Anopheles, in America at least, is responsible for the distribution of malarial troubles, while Stegomyia appears to do as much for yellow fever.
Mr. Theobald emphasizes the character of the scales on certain portions of the head, wing and body, which assists in separating species. This brings into play the microscope and, practically, that instrument must be resorted to for final determinations in some instances.
It is altogether a very interesting and useful book to the entomologist who wishes to learn what has been done in this family and who has done it. The plates are too highly colored and the figures are, therefore, misleading. The text figures, illustrating structural details, are as a whole only fair, though the point to be illustrated is always well brought out. The book maker's work is well done, and so is the printer's, while a good index adds materially to the facility with which the book may be used by the reader.
MECHANICS.
An 'Elementary Treatise on Theoretical Mechanics' by Professor W. Woolsey Johnson (Wiley and Sons, New York) is far from elementary, as the reader is supposed to have a good knowledge of differential and integral calculus. The laws of nature are, however, quite independent of any system of mathematics, and many of those discussed in this volume might be easily treated by elementary algebra and geometry. There can be no objection to the use of the calculus if its demonstrations are simpler than those of common methods, but the combination of difficult mathematics with difficult subject-matter should be avoided in an elementary text-book. The plan of the book is that usual in this subject, forces being discussed at much length, in connection with the time-rate of space or velocity, before the subject of work or energy is taken up. This plan follows the historical line of development, but it is questionable whether it is the best method for the student or for getting at practical solutions. The book contains no unsound doctrine, is concisely written in a scholarly tone, and is an able presentation of the subject under the plan adopted.