SCIENCE. 



363 



Electricity ; and we have the same warrant to consider 

 Electricity as some modification of Heat. In fact the 

 term " Radiance " would be a more distinctive appella- 

 tion than " Radiant Heat." 



As to trust in authorities, of course we must trust in 

 them as long as their explanations seem most in accord- 

 ance with facts, but no longer. Well-established facts 

 are the only trustworthy data of Science. No theory can 

 be sustained against the pressure of unconformable facts. 

 In short, every theory is in danger while a single fact re- 

 mains unexplained. For the facts of nature are so 

 closely linked that each in some way bears upon all, and 

 all upon each. And yet it is by no means advisable to 

 stop theorizing, for correct theories are themselves facts 

 of science — facts concerning forces and relations as de- 

 duced from facts concerning things. And every par- 

 tially correct theory is a footstool through which higher 

 levels of conception may be reached ; while every theory 

 proved incorrect is a warning board, advising all future 

 scientists not to waste time in following a path that leads 

 nowhere. Charles Morris. 



2223 String Garden Street, Philadelphia. 



BOOKS RECEIVED. 



Text-Book of Experimental Organic Chemis- 

 try for Students, by H. Chapman Jones. D. Van 

 Nostrand. New York, 188 1. 



Although termed a text-book, the author admits that 

 this little volume will be found of greater use as a com- 

 panion for the student in the laboratory, who wishes to 

 study organic chemistry both practically and theoreti- 

 cally. 



We recommend this volume to those who have a lim- 

 ited time at their command for study, and are not over- 

 burdsned with cash, the author having wisely restricted 

 the number of experiments, and suggested only such 

 as are available in a laboratory of the humblest pre- 

 tensions, and the use of expensive chemicals is alto- 

 gether avoided. The author has shown considerable 

 judgment in arranging this w,ork, the plan of which is ex- 

 cellent, because while the subject has been reduced to its 

 simplest form, the instructor will find all that is necessary 

 for teaching the elementary stages of practical organic 

 chemistry, and it will serve as a reliable guide to the aver- 

 age student who relies on his own resources for instruction. 



Contributions to Meteorology: being results de- 

 rived from an Examination of the Observations of the 

 United States Signal Service, and from other sources. 

 By Elias Loomis, Professor of Natural Philosophy 

 in Yale College. 



A pamphlet reprinted from the American Journal of 

 Science, being the subject matter of a paper read before 

 the National Academy of Sciences. Washington, April 

 19, 1881. 



On The Group "6" On the Solar Spectrum. 

 By William C. Winlock. From the proceedings of 

 the American Academy of Arts and Sciences. Pre- 

 sented by Professor Wolcott Gibbs. June 9, 1880. 



The most complete charts of the solar spectrum now 

 available are Kirchhoff's, which were published in 1861, 

 and Angstrom's, published in 1869. Kirchhoff employed 

 a battery of four flint-glass prisms, with a collimator 

 and observing telescope each of about 4 centim. aper- 

 ture and 49. centim focal length ; while Angstrom used 

 telescopes of about 4.6 centim. aperture, and 36.3 centim. 

 focal length, and a diffraction grating made by Nobert, 

 containing about 133 lines to the millimetre. 



Such great advances have been made very recently in 

 the construction of optical instruments, and more espec- 

 ially in the ruling of diffraction gratings, that it would now 



be possible to enlarge Angstrom's great chart almost as 

 much as he improved upon Fraunhofer's first maps. But 

 it would be an almost endless undertaking for a single 

 observer to attempt a map of the whole spectrum, from 

 the ultra-violet to the invisible red, brought to light by our 

 most powerful instruments, and accordingly most physi- 

 cists who have paid especial attention to solar spectro- 

 scopy have devoted themselves to a careful study of de- 

 tached portions which appear of unusual interest. Asa 

 contribution to this work, the following observations upon 

 the group of dark lines " b," of the solar spectrum, were 

 undertaken by Mr. Winlock, at the suggestion of Dr. 

 Gibbs, and carried on under his immediate supervision. 



A Practical Treatise on the Manufacture of 

 Starch, Starch-Sugar and Dextrine, based on 

 the German of Ladislaus Von Wagner and other au- 

 thorities, by Julius Frankel. Edited by Robert 

 Hutter. Illustrated by 58 engravings, covering every 

 branch of the subject. Henry Carey Baird & Co., 810 

 Walnut street, Philadelphia, 1881. Price, $3.50. 

 The increased manufacture of Glucose and the pros- 

 pect of this substance becoming a staple article of pro- 

 duce in the United States, makes this volume a welcome 

 addition to the excellent series of technical works pub- 

 lished by this house. 



Those about to engage in the manufacture of Glucose 

 will find this treatise an indispensable guide, and, as we 

 understand, it is the only work in the English language 

 describing in detail the processes and machinery made 

 use of in this important class of industry. 



It is stated in the preface that this subject has been 

 heretofore surrounded by more or less mystery than any 

 other manufacture of recent years, and that access to fac- 

 tories has been barred to all but workmen, and that in- 

 ventors and manufacturers of the necessary machinery 

 have refused to furnish drawings of the machines. It is 

 therefore evident that the present work, which has been 

 prepared with care, intelligence and zeal by one who is a 

 master of the subject, must be a valuable acquisition to 

 those interested in this industry. 



Mr. Frankel introduces the subject by describing the 

 Chemistry of Starch, its technology and methods of manu- 

 facture. The Chemistry of Starch-sugar is then taken 

 up and its manufacture in all its branches explained in de- 

 tail. The author concludes with an exhaustive descrip- 

 tion of Dextrine and its manufacture. 



It was Professor Kirchhoff, of St. Petersburg, Russia, 

 who made the important discovery in 181 1, that starch 

 boiled in dduted sulphuric acid is transformed into sugar, 

 but the origin of glucose manufacture dates from the time 

 of Napoleon I., when the Engl sh were blockading the 

 Continent. At the time it caused a great and general sen- 

 sation, as it was then thought that grape sugar was iden- 

 tical with cane sugar, and hence could in every respect be 

 substituted for that product. This new branch of indus- 

 try was, therefore, pursued with energy, and immense 

 quantities of starch-sugar were manufactured, but subse- 

 quently, when it was proved that this material was by no 

 means identical with cane sugar, being less soluble, of 

 less sweetness, and not at all suitable to serve as a substi- 

 tute for the former, then for a number of years the de- 

 mand ceased. Of late years a revival has taken place in 

 this industry, and in 1876 Germany alone produced in her 

 47 glucose, starch-sugar and syrup factories 100 million 

 pounds, and as we stated in a recent article 500 tons a day 

 of glucose are now produced in the United States. 



It is singular to observe that such substances as Starch, 

 Grape-sugar and Cane-sugar, which have such opposite 

 properties in some respects, are almost chemically alike. 

 If starch absorbs two molecules of water, it becomes 

 transformed into glucose (grape or starch sugar), while 

 cane sugar contains one molecule more than starch and 

 one molecule less than the starch sugar. The chemical 



