Jan. 13, 1 881] 



NATURE 



243 



between Jukussina and Yonesawa, I first found lar^e bamboo 

 plantations near the last place, about 1000 feet above sea-Ievel, and 

 37* 55' N. Between here and Niigata the temperature of the 

 coldest month mu>t differ by about 3°, the latter place being 

 situated near the sea. This gives about 30° F. for Yonesawa, or 

 about the same as at Yusaw a. Now in Great Britain, the 

 mountainous districts excepted, the mean temperature of the 

 coldest month is nowhere lower than 36°. A. WOEIKOF 



St. Petersburg, December 19, iSSo 



In my letter (vol. xxiii. p. 194) I inadvertently stated that 

 Sequoia cones were compo.'^ed of from 16 to 20 scales. I in- 

 tended to say 16 to 50, which appears to be the maximum 

 number in eitlier of the existing species. J. S. G. 



Chalk 

 The objections urged by Mr. S. N. Carvalho, jun. (vol. xxiii. 

 p. 194), to Wallace's explanation of the deposition of chalk must 

 have occurred to every geological reader of " Island Life." There 

 are very many other objections to it, and I trust to be permitted 

 to call attention to them in the Geological Magazine, as they are 

 probably too purely geological to interest the readers of Natijre. 



J. S. G. 



Average Height of Barometer in London 

 It was stated in your "Meteorological Notes" a week or two 

 ago in regard to the paper by Mr, II. 8. Eaton on the average 

 height of the barometer in London, that " the series is sufficiently 

 extended as to entitle it to be considered one of the most valuable 

 we possess in dealing with questions of secular meteorological 

 variation." 



Regarding it in the same light I have thought it worth while 

 to appily Mr. Meldrum's method for discovering the existence 

 and character of the secular variation in the sun-spot cycle. 

 Taking the period lSll-79 I find the following figures for the 

 mean cycles : — 



London 

 Animal Barometric Abnormals, Mean Cycles 

 1 years in fifth line. 



The variation of pres-ure, though not so regular as that I 

 worked out for St. Petersburg in 1879, is of an almost exactly 

 opposite character, the minimum pressure appearin'^ as in India, 

 about the time of maximum •■un-spot. and the maximum pressure 

 lagging two years behind the epoch of minimum sun-spot. These 

 results a5_Tree with the known annual rainf:ill variation in the 

 same cycle, which is likewise similar in character to that which 

 occurs in the tropics. I would suggest that the marked difference 

 between the results for London and St. Petersburg possibly nrises 

 from the close communication between England and the tropics 

 through the medium of Atlantic oceanic and atmospheric 

 currents. E. DOUGLAS ARCHIBALD 



January 4 



Experiments with Vacuum Tubes 



In my letter published in the last number of Nature I omitted 

 to say that we have compared vacuum tubes without electrodes 



with a tube containing water. A tube was filled about nine-tenths 

 fu'l of water and then sealed hermetically. It was then applied 

 to the prime conductor of the electric machine and electrified in 

 the same way as the vacuum-tubes without electrodes, and it was 

 found to behave precisely as they did. The water tube became 

 charged as a double Leyden jar, positive outside and negative 

 inside at the end next the prime conductor, and negative outside 

 and positive inside at the other end. A great tendency to 

 rupture of the glass was also observed. So far as we have been 

 able to see the mo-t perfect vacuum that I have been able to 

 obtain with the Sprengel pump has behaved as to frictional elec- 

 tricity precisely as a perfect conductor such as water. 



These experiments seem interesting in connection with the 

 discoveries of Mr. Crookes as to the properties of a very perfect 

 vacuum. No doubt it was known that flashes can be obtained 

 within vacuum tubes without electrodes ; but the properties of a 

 perfect vacuum as a conductor of electricity has not been hitherto 

 sufficiently investigated. J. T. Bottomley 



Physical Laboratory, the University, Glasgow, January 8 



Oxidation of Quinine, &c. 



In the Chemical Society's Journal for December, 1880, there 

 is an abstract of a paper by Hoogewerf and Van Dorp, pub- 

 lished m Lif/'ia's Annalen, cciv. 84-118, in which the authors 

 describe experiments on the oxidation of quinine, quinidine, 

 cinchonine, and cinchonidine. As reference is made in this 

 paper to our work upon the same subject in such a manner as 

 to lead to the inference that we had copied Hoogewerf and Van 

 Dorp, we beg to call attention to the dates of publication of the 

 various memuirs relating to the matter. 



In the Berlin Bcrichte, x. 1936 (close of 1877), Hoogewerf and 

 Van Dorp published a preliminary note on the oxidation of 

 aniline, toluidine, and quinine, and stated that they had obtained 

 amongst other products of oxidation of quinine a nitrogenous 

 acid, to which apparently they attached little importance. Of 

 this acid they gave no further account. At that time we were 

 working at the same subject, and had come to some important 

 conclu'-ions. 



As Hoogewerf and Van Dorp's results contained nothing re- 

 lating to quinine in addition to what had been observed by Cloez 

 and'Guignet many years previiusly, we did not consider that they 

 were entitled to claim that this field of work should be reserved 

 for them. We therefore sent our paper to the Chemical Society, 

 before which it "as read on January 19, 1S78 (see also Berlin 

 Bericlite, xi. 324). In this paper we stated that the acid obtained 

 by us from quinine was probably identical with dicaibopyridenic 

 acid. That the acid was a pyridenic acid we had no doubt, but 

 owing to the difficulty f'f purification we bad not been able to 

 establish its formula with certainty. 



In the Berlin Berichte, xii. 158-161, was published a second 

 paper by Hoogewerf and Van Dorp (read before the Berlin 

 Chemical .Society on January 27, 1879), on the acid obtained 

 from quinine, giving no analyses, but stating that the acid was 

 /;•/- and not (//carhopyridenic acid, thus confirming our result in 

 its important bearing, viz. the connection between the quinine 

 and pyridine series. In the same paper they suggested that an 

 acid obtained by ihem from quinidine and cinchonine was 

 identical with the quinine acid. 



Immediately on receipt of the number of the Berlin Berichte 

 c.)ntaining Hoogewerf and Van Dorp's paper, we forwarded to 

 the secretary of the Chemical Society our second memoir, which 

 contained numerous analyses of the acid obtained, not from 

 quinine only, but also fron^ the allied alkaloids, quinidine, 

 cinchonine, and cinchonidine, together with a full description 

 and analysis of all its important salts. That paper was read 

 before the Society on February 20, 1S79. 



In Liedix's Aniiah-n, cciv. 84-n8 (July 31, 1880), or a year 

 and a half after the publication of our second paper, Hoogewerf 

 and Van Dorp published analyses of the acid and many of its 

 salts, prepared from three alkaloids, the results confirming our 

 own in all points. 



Our claim, w hich the above dales fully substantiate, is to have 

 been the first to establish the connection between the quinine and 

 pyridine series, and to have proved that the four alkaloids all 

 gave the same oxidation product. 



Prof. Butlerow of St. Petersburg, immediately on appearance 

 of our first paper, when engaging in work closely connected 

 with, but not overlapping ours, wrote suggesting that we should 



