120 



SCIENCE. 



CORRESPONDENCE. 



[ The Editor does not hold himself responsible /or opinions expressed 

 by his correspondents. No notice is taken of anonymous communi- 

 cations^ 



MICROSCOPY. 



To the Editor of " Science :" 



Dear Sir : — I am authorized by the President of the 

 American Society of Microscopists to announce to its 

 members, and to all others who may be interested, that 

 the Executive Committee have decided, by aji almost 

 unanimous vote, to accept the invitation received from the 

 Tyndall Association of Natural Science, of Columbus, 

 Ohio, and to call the next meeting of the Society at that 

 place on Tuesday, August 9, 1881, (the week previous 

 to the meeting of the American Association for the Ad- 

 vancement of Science, at Cincinnati). 



Permit me to add a word upon another matter. The 

 proceedings of the American Society, which should have 

 appeared two months ago, have been unavoidably de- 

 layed by circumstances which I shall explain to members 

 at the time of issuing the volume. The latter is now in 

 the press, and will be sent out before the end of the 

 month. Albert H. Tuttle, Sec'y. 



Columbus, Ohio, March 1, 1881. 



BOOKS RECEIVED. 



Bacteria. By Dr. Antoine Magnin, General Sec- 

 retary of the Botanical Society of Lyons, &c., &c. 

 Translated by George M. Sternberg, M. D., U. S. A. 

 Boston — Little, Brown, & Company. 1880. Price 

 $2.50. 



The present translation of Dr. Magnin's work by Dr. 

 Sternberg will be welcome in all English speaking coun- 

 tries, ana we trust its circulation may remove much of 

 the ignorance which exists on this subject, among a 

 large class of professional men, who would perhaps be 

 ashamed to confess their want of knowledge. 



Among physicians Dr. Magnin's work on the Bacteria 

 should find a wide range ot readers ; to many it will 

 read like a revelation, and may be the means of develop- 

 ing original ideas, which may give them a fresh impulse 

 in their profession. 



It has been a hard struggle with Nature, accompanied 

 by the greatest difficulties, to solve the many problems 

 involved in the phenomena attributed to Bacteria. One 

 hundred and fifty years have passed since Leeuwenhoek, 

 the Father of Microscopy, wrote the first paper on the 

 subject, and Dr. Magnin occupies thirty-one pages of his 

 work in recording a Bibliography of the works of those 

 who have since contributed papers. 



By the aid of this large amount of literature treating 

 on Bacteria, supported by his own experience, Dr. Mag- 

 nin has produced a work, a careful perusal of which will 

 greatly reduce the difficulties of further investigations in 

 solving the many problems still waiting for solution. 



A full classification of the genera and species of Bac- 

 teria is given, with sufficient descriptions of their forms 

 and characteristics to make their identification an easy 

 task, and although this classification is merely provision- 

 al, its practical utility for student's work is not impaired. 



We observe ten full-sized plates of engravings, each 

 having from four to twenty-two illustrations of Bacterian 

 forms. 



No person possessing a Microscope should be without 

 this book, and it should be closely studied by every phy- 

 sician. 



The temptation is great to enter into a description of 

 the varied contents of the work, but the subject is too in- 

 tricate to be disposed ot in a short paragraph and must be 

 reserved tor future treatment. 



Bacteria are of all beings the most widely diffused ; 

 we meet with them everywhere, in the air, in the water, 

 upon the surface of solid bodies, in the interior ol plants 



and animals. They are the cause of disease, and the 

 great agent in putrefaction, and yet the continuance of 

 life on this globe would not be possible without them ; 

 they are so minute that some defy measurement with the 

 highest powers of the microscope, but they become a 

 mighty factor in the economy of creation by reason of their 

 wonderful powers of reproduction, for in twenty-four hours 

 the product of a single bacterium by division amounts to 

 sixteen millions of individuals, and at this rate the ocean 

 itself — calculating it equal to two-thirds of the ter- 

 restial surface, with a mean depth of one mile, equalling 

 920,000,000 cubic miles — would be filled with Bacteria in 

 five days from a single germ, supposing the multiplica- 

 tion to be continued with the same conditions. 



Fortunately researches of microscopists have brought 

 to light facts regarding these organisms which enable 

 man to control their prodigious reproductive powers, and 

 our knowledge relating to Bacteria will probably at 

 length be acknowledged as one of the greatest victories 

 of modern science. 



NOTES. 



A Process for the Total Destruction of the Or- 

 ganic Matters in the Detection of Poisonous Mineral 

 Substances. — From 100 to 500 grms. of the suspected mat- 

 ter are mixed in a large porcelain capsule with one-fourth 

 its weight of the acid sulphate of potassa, and then with its 

 own weight of fuming nitric acid. The action is very vio- 

 lent at first, and requires afterwards the aid of a slight heat. 

 Here it is proper to stop if it is merely needful to search 

 for arsenic or antimony. A large excess of pure concen- 

 trated sulphuric acid (1.845 S P- g r -) is then added, and the 

 mixture is heated to near the boiling point of the acid. 

 More acid is added from time to time till the mixture be- 

 comes pale and limpid. To complete the destruction of the 

 last traces of organic matter it is well to let the liquid cool, 

 add a few crystals of pure potassium nitrate, and heat again 

 till abundant white vapors of sulphuric acid are evolved. 

 The saline mass when cold is dissolved in boiling water, 

 made up to 1 litre, and without previous filtration it is sub- 

 mitted to electrolysis by means of 4 Bunsen elements or a 

 Clamond gas-battery. The negative platinum electrode be- 

 comes covered with a grey, blackish, or metallic coating. 

 The action should be prolonged for twenty-four hours. If 

 mercury is suspected a plate of gold should be used at the 

 negative pole instead of platinum. If arsenic or antimony 

 is sought for before the addition of the sulphuric acid, the 

 carbonacious mass is cooled, powdered, and treated with 

 boiling water. The solution thus obtained is examined 

 as proposed by Dr. A. Gautier. {Comptes Rendus, August, 

 i875)- — A. G. Pouchet. 



Determination of Carbonic Acid in the Air. — The 

 authors, after referring to the discordant results obtained in 

 the determination ol atmospheric carbonic acid, describe 

 their method. The carbonic acid is fixed by an absorbent 

 body, from which it is afterwards set at liberty and meas- 

 ured by volume. As an absorbent they use pumice stone 

 saturated with solution of potassa, and contained in a tube 

 drawn out at both ends. The tubes are washed with sul- 

 phuric acid, filled with small fragments of pumice, calcined 

 with sulphuric acid, and introduced while hot. The pum- 

 ice is saturated with a given volume of potassa lye, operat- 

 ing in air deprived of carbonic acid. The lye is prepared 

 by dissolving 1 kilo, potassa in 1.400 litres of water, and 

 adding 200 grms. hydrated baryta to remove sulphates and 

 carbonates. The tubes, prepared beforehand and sealed, 

 are opened at the place of operation, and se.ilcd again after 

 200 litres of air have been passed through. — A. Muntz 

 and E. Aubin. 



Residues from the Manufacture of oils from Schists. 

 The solid residues serve for the manufacture of alum, and 

 may become an important source of lithia. The acid tarry 

 matters contain sulphates of the bases of the pyridic series, 

 especially of corindine, rubidine, and viridine. Aniline is 

 not sensibly present. The insoluble portions and the alka- 

 line tars contain peculiar phenols, thymols /3 and y. There 

 is no ordinary phenic acid, and very little thymol a. — Gas- 

 ton Bong. 



