jMly 14, 1887] 



NA TURE 



243 



We have very little to say except in favour of this 

 work, which is certainly one of the most important of 

 recent contributions to systematic botany ; but we should 

 have liked to see a closer adherence to established usage 

 in the application of certain botanical terms. To use the 

 terms monoecious and dioecious in relation to the indi- 

 vidual receptacles as well as the whole tree is perplexing, 

 and also unnecessary, because suitable terms for express- 

 ing these distinctions are current, and even employed by 

 the author himself in some passages. VV. B. \\. 



OUR BOOK SHELF. 



Year-book of Pharmacy for 1886. (London: Churchill, 



1887.) 

 General Index to Year-books of Pharmacy, 1864-1885. 



(London: Churchill, 1886.) 



The "Year-book of Pharmacy" tor 1886 contains 

 a larger number than usual of abstracts of papers. 

 Amongst the most interesting of them are perhaps 

 those treating of coca and substances obtained from it. 

 It- appears that when the active principle, cocaine, is 

 heated with water it decomposes, losing methyl (CH3), 

 which is replaced by hydrogen. The product of this 

 decomposition is benzoyl-ecgonine, which can again be 

 converted into cocaine by heating with methyl iodide 

 and methyl alcohol. The replacement of methyl by 

 hydrogen in the conversion of cocaine into benzoyl- 

 ecgonine produces a very marked change in the physio- 

 logical action of the substances, for while cocaine is 

 distinguished by its extraordinary power of paralyzing 

 the sensory nerves and thus producing anaesthesia of 

 any part to which it is applied, this power is completely 

 absent in benzoyl-ecgonine. Benzoyl-ecgonine, however, 

 has a physiological action very closely allied to that of 

 caffeine — a circumstance which is very interesting in 

 relation to the use of coca and coffee as a beverage. 



Another substance used as an intoxicating drink in the 

 South Sea Islands — namely, Kava, obtained from the root 

 of Piper methysticiiui — has been found, like cocaine, to 

 have a powerful local anjesthetic action. 



Other abstracts of great interest are those which relate 

 to ptomaines and leucomaines, or alkaloids formed from 

 the decomposition of albuminous matters either outside 

 or inside of the body. These alkaloids are becoming 

 more and more important from the fact that they are 

 now recognized as not only causing poisoning where meat 

 has been taken in a state of putrefactive change, but as 

 causing abnormal symptoms in some diseases. Thus it 

 has been found that in typhoid fever a large quantity of 

 ptomaines occur in tbe faeces, and it is supposed by one 

 writer that the utility of tisanes in illness may be due to 

 their aiding the removal of these alkaloids from the body 

 through the kidneys. 



By cultivating the comma-bacillus in broth, an alkaloid 

 has been obtained which appears to be identical with that 

 already isolated from the dejecta of cholera patients. In 

 relation to these alkaloids produced in the body, it is very 

 interesting to note that alkaloidal substances may be 

 formed by the action either of ammonia or of compound 

 ammonias on glucose. 



A number of new alkaloids have been isolated from 

 plants, and the actions of several of these are described. 



The General Index to the " Year-books of Pharmacy " 

 for the Years 1864- 1885 inclusive is of great service, 

 saving much time, and enabling one not only to find any 

 paper readily, but to see at a glance what work has been 

 done on a particular subject within the last twenty 

 years. 



A B C Five-Figure LojJdriihins. By C. J. Woodward 

 (London : Simpkin Marshall and Co., 1887.) 



To those who work in physical and chemical laboratorie 

 this little book will be an immense help, for, in th 

 ordinary work of the laboratory, errors of experimen 

 exceed any error of calculation introduced by five-figur 

 logarithms, while the time saved in calculation is ver 

 great. 



The tables are indexed ledger- fashion, so that the re 

 quired mantissa may be found in a moment. The diffei 

 ences for the 5th and 6th figures of sequences are found b 

 using side letters denoting the line at the foot of eac 

 table in which the required difference is presented. Muc 

 greater accuracy is obtained by the last figure of certai 

 mantissiE having dashes above and below to indicat 

 departures from the normal difference. At the end ar 

 added a few chemical and physical constants and table: 

 including some on gas analysis. 



LETTERS TO THE EDITOR. 



[The Editor does not hold himself responsible for opiniot 

 expressed by his correspondents. Neither can he unde. 

 tcike to retiirn, or to correspond with the writers ^ 

 rejected manuscripts. No notice is taken of anonymoi 

 com m un ications. 



[ The Editor urgently requests correspondents to keep the\ 

 letters as short as possible. The pressure on his j/a. 

 is so great that it is impossible otherwise to insure ti 

 appearance even of communications containing interestin 

 and novel facts.] 



Lighthouse Work. 



In the second of the very interesting articles on " Lighthoui 

 Work in the United Kingdom," by Mr. J. Kenward, which hai 

 appeared in your pages, some words are used, not intentionall; 

 I believe, but which, by those who are unfamiliar with tf 

 subject, might be construed in such a way as to deprive the lai 

 Mr. Thomas Stevenson of the credit due to him as the inventc 

 of the dioptric mirror. The following is an extract from M 

 Thomas Stevenson's " Lighthouse Construction and Illumin; 

 tion," published in 1881, which puts the matter on a corre 

 footing : — 



" Mr. y. 7. Chance's Improvements of 1862 on Stevenson 

 Dioptric Spherical Mirror. — Mr. Chance proposed to genera 

 the prisms of the spherical mirror round a vertical instead of 

 horizontal axis, and also to arrange them in segments. He sa; 

 (Min. Inst. Civ. Eng. vol. xxvi.) : — ' The plan of generatir 

 the zones round the vertical axis was introduced by the autho 

 who adopted it in the first complete catadioptric mirror whic 

 was made, and was shown in the Exhibition of 1862 by tl 

 Commissioners of Northern Lighthoases, for whom it was coi 

 structed, in order to further the realizing of what Mr. Thorn; 

 Stevenson had ingeniously suggested about twelve yea 

 previously. During the progress of this instrument the id< 

 occurred to the author of separating the zones, and also 1 

 dividing them into segments like the ordinary reflecting zones 

 a dioptric light ; by this means it became practicable to increai 

 considerably the radius of the mirror, and thereby to rend' 

 it applicable to the largest sea light, without overstepping tl 

 limits of the angular breadths of the zones, and yet withoi 

 being compelled to resort to glass of high refractive power.' 



" There can be no doubt of the advantage of these improvi 

 ments, and it is without any intention of derogating from M 

 Chance's merit in the matter that it is added that my first id( 

 was also to generate the prisms round a vertical axis. But tl 

 flint ylass which was necessary for so small a mirror coul 

 not be obtained in large pots, and had to be taken out in vei 

 small quantities on the end of a rod and pressed down into tl 

 mould. I was therefore obliged to reduce the diameter of tl 

 rings as much as possible ; and it was thought by those whom 

 consulted at the time (Mr. John Adie, Mr. Alan Stevenson, ar 

 Prof. Swan) that by adopting the horizontal axis the mo 

 import£nt and most useful parts of the instrument near the ax 

 would be more easily executed, inasmuch as those prisms we; 

 of very much smaller diameter. Mr. Chance not only adoptc 



