March 4, 1 880] 



NATURE 



4i7 



kind are to be expected rather than severely commented 

 on ; especially considering the imperfect material which 

 the authors had in some cases at their command, and the 

 doubt which still hangs over the origin and preparation 

 of some drugs familiar to pharmaceutists in this country. 

 Only in a few instances is the species depicted for the first 

 time ; but in all other cases it has been, where possible, 

 drawn afresh either from a living plant or from a dried 

 specimen in the herbarium of the British Museum. No 

 botanist's or pharmaceutist's library will be complete 

 without this work, which will long be the standard book 

 of reference on all subjects connected with the origin, 

 preparation, and uses of the products of medicinal plants. 



LETTERS TO THE EDITOR 



I The Editor does no! hold himself responsible for opinions expressed 

 by his (Orrespondt nts. Neither can he undertake to return, or 



to correspond with the writers of, rejected manusci ._. 

 notice is taken of anonymous communications. 

 [ The Editor urgently requests correspondents to keep their letters as 

 short as possible. The pressure on his space is so gicat that it 

 is impossible otherwise to ensure the appearance cz-c/i of com- 

 munications containing interesting and novel facts. \ 



Novel Source of Frictional Electricity 

 I wish to put on record the fact which I communicated to the 

 Thysical Society la?t week, that the motion of a chalk cylinder 

 under a metallic surface generates an electric current having an 

 E. M. F. of rather over one-third of a volt. 1 The strength 

 of the current depends on the rate of rotation and the pressure 

 i'ii the surface of the chalk; the latter simply diminishes the 

 internal resistance, which is of course very high. The discovery 

 is due to a suggestion made to me so long ago as last November, 

 by Prof. Silvanus Thompson, who wished me to try whether the 

 motograph receiver of the Edison telephone could be used as a 

 transmitter. I was unsuccessful at the time, but under favour- 

 able circumstances I find the voice is faintly but accurately 

 transmitted on speaking into the receiver, so long as the chalk is 

 made to rotate. W. F. Barrett 



Royal College of Science, Dublin, March I 



Carnivorous Wasps 



In Nature, vol. xxi. p. 30S, there is a statement as to an 

 exceptional case of carnivorous habits in honey-bees, which I 

 can believe all the more easily, as I know that bees, apparently 

 from a lack of their usual food, occasionally attack plums and 

 other fruits, of which in ordinary seasons they take no notice. 



Several years ago, w hen grouse-shooting in the county of 

 Sutherland, I observed a wasp (a rare insect in those parts) 

 struggling with something on the ground, and found that it was 

 in the act of devouring a caterpillar, which was still alive, but 

 considerably mangled by the mandibles of the wasp. la 

 Sutherland this species of smooth, green caterpillar is abundant, 

 and is a favourite food of the black game, whose crops are 

 nes full of it. 



U it not unusual for the common wasp to eat living creatures 

 ■ ■:' any sjrt ? 



To all of our party the thing appeared extraordinary, and I 

 thought of writing to Nature at the time, but omitted doing sa 

 until reminded of the o:currence by reading about bees devi luring 

 moths.. David Wedderburn 



March 2 



Stags' Horns 

 Miss Bird sends me, in answer to my inquiry, the following 



additional information as to the cast stag,' horns found in the 



■ alleys of the Rocky Mountains : — 



•'There are several small valleys opening from F.stes Park, 



Colorado, which were resorted to by elks for the purpose of 



shedding their horns. In one of these, at the time of my visit 



in 1S73, 'hey lay quite thick. Some were quite recent, and 



others were bleached with age. 1 have not myself seen any but 



elk horns, but hunters told me that the spotted deer resorted to 



a valley near Long's Peak to shed their horns. I al-o came 



> The chalk had been impregnated snme months before with a solution of 



phosphate of soda, but when used was practically dry, nnd had a hard 



mooth surface, almost like polished marble. 



upon a large number of elk horns in a valley near Tarryall 

 Creek, South Park, Colorado. 



" Near Estes Park some of the horns were so recent and in 

 such good order, that I hoped to procure some to tal 

 but on examining even the most recent closely, I found that they 

 were all more or le-s injured by abrasion 'against 

 substance, as I thought. Two hunters, named Comstoch and 

 Nugent, told me thit with good glasses, from certai 

 which they named, they had seen the elk violently rubbing their 

 heads against the rocks, with the view, as they supposed, of 

 ridding themselves of their horns. I am s^-ry that I cannot 

 contribute more accurate observations on the subject." 



B. W. S. 



PIERRE ANTOINE FA VRE 



■\1TE ate called upon to chronicle the death, at Mar- 

 * * seilles, on February 17, of Prof. Pierre Antoine Favre, 

 whose name is so intimately connected with the history of 

 thermo-chemistry. Born at Lyons, February 20, 1813, he 

 entered upon a career of scientific study at Tan's, devoting 

 himself especially to chemistry, under the direction o'f 

 Peligot. After completing the usual course of study, he 

 accepted a position in the laboratory of Prof. Atidral, 

 under whose guidance, as well as under that of Dr. Jecker, 

 he made a series of researches in physiological chemistry. 

 Returning to his former teacher, Prof. Peligot, at the 

 Conservatoire des Arts et Metiers, in the capacity of 

 assistant, he speedily created a reputation by his investi- 

 gations in thermo-chemistry, and was appointed Assistant 

 Professor of Chemistry in the Medical' Faculty of Paris. 

 After filling this position for nine years, Favre was 

 appointed to the Chair of Chemistry in the Scientific and 

 Medical Faculties of Marseilles. Here his marked 

 abilities caused his election as Dean of the Scientific 

 Faculty. Failing health forced him to give up the active 

 duties of his professorship in 1878. 



Favre's first research (1843) was on the atomic weight 

 of zinc, and had in view the ascertaining of its being a 

 whole multiple of that of hydrogen. Following this (1844) 

 came an extensive research on mannite, yielding a number 

 of new and important reactions. The most noteworthy 

 of his investigations in physiological chemistry were 

 those on the blood of persons suffering from scorbutic 

 complaints (1S47I, in which he signalled an increase of 

 fibrine and a decrease of the number of corpuscles and on 

 the composition and properties of the perspiration of the 

 human body (1852). For this latter purpose he succeeded 

 in collecting no less than 40 litres of perspiration, a 

 quantity which allowed him to discover the hydrotinic 

 acid peculiar to this liquid, as well as to show the pre- 

 dominating presence of NaCl among its soluble con- 

 stituents. Favre's only contribution to technical chemistry 

 was his proposal in 1S56 to decompose the refuse sulphides 

 of the soda works by hydrochloric acid, and conduct the 

 sulphuretted hydrogen liberated to the pyrite furnaces or 

 into solution of sulphurous acid. 



Apart from the above-mentioned researches, his career 

 as an investigator — extending over a period of nearly 

 thirty years — was devoted almost exclusively to solving 

 the problems of thermo-chemistry, devising necessary 

 apparatus of the most exact precision, gathering an 

 enormous mass of experimental data, correcting and 

 comparing the results of other workers, and elaborating 

 the entire structure of this important branch of chemical 

 physics. For the first six years J. T. Silbermann, like 

 himself at the time assistant in the Conservatoire des 

 Arts et Metiers, was associated with him in the investi- 

 gations. The first requisite for the correct determination 

 of thermic equivalents was a series of calorimeters of the 

 utmost exactitude, and this want was met by the construc- 

 tion of the two well-known pieces of apparatus bearing 

 the names of the two chemists. The first, intended for 

 the determination of the heat given off by reactions 

 between solids and liquids, consists of a large mercurial 



