•Tri Y -2, 1900.] 



KNOWLEDGE. 



155 



German t<>rm " geist, " signifying " spirit." Van 

 Hohnont t«lls us of liis " gas sylvestre, " observod rising 

 from beer and fermenting liquids of various kinds, and 

 was the tirst to clearly distinguish between this gas 

 (cai-bon dioxide) ajid ^hc alcoliol remaining in solution. 

 To him we owe the dictum, fermentum vojatiliset, quod 

 alias in cai'bonem mut<itur, and in his " Opera omnia, 

 published in 1707. together with, as Huxley remarked, 

 a very needful '" Clavis ad obscuriorum sensum referen- 

 dum, ' may be found much of interest concerning the 

 learning of his times. Alcohol meant not only spirits 

 of wine, but various other things as well, a fact we may 

 convey by quoting Nathan Bailey s definition. 

 " Alcohol," says this early lexicographer, " is the pure 

 subs*^ance of anything separated from the mere gross, 

 a very fine and impalpable powder, or a very pure, well- 

 rectified spirit." Van Helniont was fain to attribute 

 to ferment vitality the origin of all animals, whilst the 

 lato Julius von Sachs records in his " History of 

 Botany " the belief of Dedxi, who, in 1685, evolved 

 similar ideas regarding the vegetable world. We must 

 not pass over the learned distinction of Silvius de la Boe 

 who threw much light on the knowledge of the six- 

 teenth century, by distinguishing between the nature of 

 gas evolved during fermentation and the evolution dis- 

 cerned when acids aie added to alkalies. The first he 

 regarded as incidental to the process of decomposition, 

 whilst the latter attended the formation of a definite 

 chemical compound. 



Johann Joachim Bceher made the discovery that only 

 sweet substances are fermentable, and that, contrary 

 to the theorv of Basilus Valentinus, the alcohol pro- 

 duced was a new substance, arising from the act of fer- 

 mentation. He makes, also, many sagacious discriminar 

 tions between putrid decompositions and alcoholic fer- 

 mentation, but was never quite able to shake off the 

 influence exerted by the fascinations of alchemy. Ernst 

 Stahl, however, whose thoughts lie recorded in a curious 

 old German work, published in 1734, may be defined as 

 a chemist, in contradistinction to a follower of alchemy 

 and its wild alluring dreams. " A body," says Stahl, 

 in the work alluded to, " which is undergoing decom- 

 position is able, when brought into contact with another 

 body not yet decomposing, to excite in this new body 

 a similar process of breaking up ; or the vibrations 

 which arc going on in the first body are able to com- 

 municate themselves to a second body of like nature, 

 which was previously in a quiescent condition." In 

 these words it is easy to discern the germ-thoughts 

 destined to be afterwards enlai-ged upon by Justus von 

 Liebig, and in some measure by that acute mathe- 

 matician J. von Nacgcli. And, further, Stahl set 

 in motion a branch of knowledge nowadays much ad- 

 vanced, to wit, that concerning the spread of diseases 

 by contagion and infection. 



The study of organic structxrrcs and materials from 

 a chemical standpoint dates from the year 1701, when 

 Hermann Boerhaave was appointed Lecturer in Medi- 

 cine, and, later, Professor of Chemistry and Botany, 

 at the University of Leyden. Geber, as we have seen, 

 devoted his life to researches among the inorganic 

 materials around him, and had, doubtless, distilled, 

 sublimed, and precipitated every suspiciou.s-looking 

 mineral or fluid that crossed his path, and now Boer- 

 haave, nearly seven centuries afterwards, proceeds to 

 distil, sublime, and collect from organic sources. This 

 great master directed his attention, like all other great 

 men of science, to the mysteries of fermentation and 

 putrefaction, arriving at the conclusion that only suli- 



stances of vegetable origin undergo fermentation, whilst 

 animal matters suft'er putrid decomposition. 



The chemical knowledge surrounding fermentation 

 takes its starting point from the year 1774, when 

 Priestley and Scheele, independently, discovered oxygon. 

 By consulting Priestley's autobiography, we learn how 

 his great discoveries were inspired by a visit to a 

 brewery, which happened to be situated in close proxi- 

 mity to his residence. J I is curiosity was aroused by 

 observing the bubbles of gas that ascended tlirougii 

 the beer during the process of fermentation. This 

 gas was carbonic acid, and with it Priestley iiKinutac-- 

 tured the first bottle of so-called soda-water. 



Lavoisier first studied fermentation from a rational 



point of view. This great chemist observed how, during 



the progress of fermentation, sugar was decoiii))osed, 



and ho regarded this decomposition as the breaking up 



of a complicated oxide, to wit, sugar, into substances 



containing less oxygen. These substances, formed in 



normal fermentations, were deemed by Lavoisier to 



l)e alcohol, carbonic acid gas, and acetic acid, and if 



we turn over the pages of his '' Elements de Cliemie, 



which work was translated by Robert Kerr in 1790, 



we shall find various quantitative analyses, worked out 



by the reformer. They do not, of course, bear well the 



search-light of modern criticism, but in later years, 



Gay-Lussac and others arose to set such matters aright, 



and to give us accurate empirical formuhe for both 



elcohol and sugar. 



" . ^ 



Hcttcrs. 



[The Editors do not hold themselves responsible for the opinions 

 or statements of correspondents.] 



IS THE STELLAR UNIVERSE FINTTK? 



TO THE EDITORS OF KNOWLEDGE. 



Sirs, — With regard to the correspondence on the 

 above subject which has recently appeared in your 

 columns, I would beg to point out that there appears 

 to be some misapprehension in the minds of your 

 correspondents regarding the relation of Mie " Galaxy 

 to tlif whole, vkihh alfUiir iiiiirerxr. The general opinion, 

 I believe, is that the Galaxy (to which our sun belongs) 

 is merely one amongst many huge star-groups, which, 

 owing to their very great distance, and to the fact that 

 we are ovt^ifle of them, appear to us as star-clusters, and 

 sometimes possibly as nebula. If it is intended to 

 confine the discussion to the " Galaxy " alone, then I 

 may say that its general shape, and our position in it — 

 but not, so far as I am aware of, its mean depth or 

 dimensions — are fairly well understood. If the \rliiilc 

 of the visible stellar universe is to be included, then the 

 question wears a different aspect entirely, and becoines 

 more foniiidalile than I should care to deal with. 



AUTIIUH Ed. MlTI'llEM.. 



A LARGE METEOR. 



TO THE EDITORS OF KNOWLEDGE. 



Sirs, — I hope other of your readers besides myself 

 observed a large meteor which was visible here at 

 8.10 p.m. on the 5th inst. When I had my attention 

 called to it, it appeared to be moving rather slowly 

 cast to south, about parallel to the earth's surface, and 

 it disappeared with a pale green flash of light, leaving 

 a dull red spark. It was quite day-light as well as 

 moon-light at the time. W. E-Mip. 



Leicester, May 12th, 1900. 



