6o 



SCIENCE. 



[Vol. XVIII. No. 443 



istry (work to begin in 1893); Ferdinand Sanford, formerly of 

 Lake Forest University, professor of physios ; Charles David Marx, 

 formerly of the University of Wisconsin, professor of civil engi- 

 neering; Joseph Svpain, formerly of Indiana University, professor 

 of mathematics ; Horace Bigelovr Gale, formerly of Washington 

 University, St. Louis, professor of mechanical engineering; 

 Charles Henry Gilbert, formerly of Indiana University, professor 

 of vertebrate zoology ; Douglas Houghton Campbell, formerly of 

 Indiana University, professor of cryptogamic botany; George 

 Mann Richardson, formerly of Lehigh University, assistant pro- 

 fessor of inorganic chemistry; Louis Alexander Buchanan, for- 

 merly of the St. Louis Polytechnic Evening School, foreman of 

 the wood- working shop; and Daniel Kirkwood, formerly of In- 

 diana University, non-resident lecturer on astronomy (resident in 

 May). 



— The necessity of devoting to sleep several hours in each day, 

 says the Lancet, is too obvious to admit of serious question. The 

 proper selection of these hours is also, for those who would pro- 

 long and usefully employ life, a very needful consideration, 

 though its importance may to some be less evident. We have all 

 met with persons, outside of hospitals and of parliament, who do 

 half or more of their daily work after nightfall, and sleep long 

 after earlier rising men are awake and busy. Some of these are 

 wont to extol the comfort of their morning slumbers. They de- 

 scribe as immense the refreshment they receive from six or seven 

 hours thus agreeably spent, and no wonder, for the sense of pres- 

 ent satisfaction must be very marked, and that for definite reasons. 

 Man, in common with most of the animal creation, has accepted 

 the plain suggestion of Nature that the approach of night should 

 imply a cessation of efifort. If he ignores this principle his work 

 is done against inherited habit, and, so far, with additional fa- 

 tigue. It follows, too, from our ordinary social conditions, that he 

 must use artificial light, and sustain its combustion at the cost of 

 his own atmosphere. Naturally, therefore, when he does rest, his 

 relief is in proportion to his weariness. As in many other cases, 

 however, sensation is not here the most reliable guide to judicious 

 practice. Established custom affords a far truer indication of the 

 method most compatible with healthy existence. The case of the 

 overworked and the invalid lends but a deceptive color to the ar- 

 gument of the daylight sleeper. In them excessive waste of tis- 

 sue must be made good, and sleep, always too scanty, is at any 

 time useful for this purpose. For the healthy majority, however, 

 the old custom of early rest and early waking is certain to prove 

 in future, as returns of longevity and common experience alike 

 show that it has proved in the past, most conducive to healthy 

 and active life. 



— The results of an investigation concerning the cause of the 

 insolubility of pure metals in acids, contributed by Dr. Weeren 

 to a recent number of the BerUihte, are given in abstract in Nature 

 of July 16. De la Rive, so long ago as the year 1830, pointed out 

 that chemically pure zinc is almost perfectly insoluble in dilute 

 sulphuric acid. Hitherto, however, the hypotheses put forward 

 attempting to account for this singular fact have been any thing 

 but satisfactory. The theory of Dr. Weeren is extremely simple, 

 and is fully supported by the most varied experiments, physical 

 and chemical. It may be stated as follows: "Chemically pure 

 zinc and also many other metals in a state of purity are insoluble 

 or only very slightly soluble in acids, because, at the moment of 

 their introduction into the acid, they become surrounded by an 

 atmosphere of condensed hydrogen, which under normal circum- 

 stances effectually protects the metal from further attack on the 

 part of the acid." It is found that when a piece of pure zinc is 

 immersed in dilute sulphuric acid, a slight action does occur during 

 the first few succeeding moments, zinc sulphate and free hydrogen 

 being formed in minute quantity. The free hydrogen, however, 

 instead of escaping, becomes condensed by the molecular action 

 of the zinc upon the surface of the latter, and is retained there 

 with great tenacity as a thin mantle of highly compressed hydro- 

 gen gas, capable of affording perfect protection against further 

 inroad of the acid. The experiments from which this simple and 

 very probable explanation has been derived were briefly as follows. 

 The amount of chemically pure zinc dissolved by the acid was first 



determined. It was, of course, an exceedingly minute quantity. 

 Considering this amount as unity, it was next sought to determine 

 what difference would be effected by performing the experiment 

 in vacuo, when of course the escape of the hydrogen would be 

 greatly facilitated. The solubiUty was found under these circum- 

 stances to be increased sevenfold. Next the experiment was per- 

 formed at the boiling temperature of the dilute acid, first when 

 ebullition was prevented by increasing the pressure, and secondly 

 when ebullition was unhindered, thus again facilitating the re- 

 moval of the hydrogen film. In the first case, when ebullition 

 was prevented, the solubility was practically the same as in the 

 cold ; while in the second case, with uninterrupted ebullition, the 

 solubility was increased twenty-four times. Finally, experiments 

 were made to ascertain the effect of introducing into the acid a 

 small quantity of an oxidizing agent capable of converting the 

 hydrogen film to water. When a little chromic acid was thus 

 introduced the solubility was increased 175 times, and when 

 hydrogen peroxide was employed the solubility was increased 

 three-hundred-fold. The explanation of the ease with which the 

 metal becomes attacked when the ordinary impurities are present 

 is that the hydrogen is not then liberated upon the surface of the 

 zinc, but rather upon the more electro-negative impurities, leav- 

 ing the pure zinc itself open to the continued attack of the acid. 

 The same of course occurs when a plate of platinum is placed in 

 contact with a plate of pure zinc in the acid. The action of 

 nitric acid, the only common acid which does attack pure metals, 

 is evidently due to the oxidation of the hydrogen film by further 

 quantities of the acid, with formation of water and production of 

 the lower oxides of nitrogen, and even under certain circumstances 

 of ammonia. 



— The regular quarterly meeting of the Michigan State Board 

 of Health was held at Lansing, July 14. The most important ac- 

 tion taken was to direct the secretary to publish a brief pamphlet 

 telling how to restrict and prevent consumption, the pamphlet 

 having been adopted by the board after very careful considera- 

 tion. This pamphlet states that " consumption is the most com- 

 mon and fatal disease," " that the number of deaths which actu- 

 ally occur in Michigan from consumption is probably over twenty- 

 five hundred per year," that " consumption is now known to be a 

 communicable disease," and that " a large part of this mortality 

 can and ought to be prevented." The pamphlet describes the 

 bacillus which causes consumption and which is in the sputa of 

 consumptives, cites instances where consumption has been com- 

 municated by the sputum dust containing these germs, and em- 

 phasizes the importance of destroying the sputa of consumptives. 

 The pamphlets on the restriction and prevention of the other most 

 dangerous communicable diseases, diphtheria and scarlet-fever, 

 were ordered reprinted for distribution among the neighbors of 

 those sick with those diseases throughout the State. A proposed 

 pamphlet on the " Restriction and Prevention of Measles " was 

 thoroughly discussed by paragraphs, amended, and the secretary 

 was directed to print and distribute the document for instruction, 

 and as an aid in the restriction and prevention of this disease, 

 which the board declares is a disease ' ' dangerous to the public 

 health," that causes many more deaths in Michingan than small- 

 pox does, and which should be dealt with according to the laws 

 in Michigan. 



— In the May number of the Journal de Botanique, says Nature, 

 MM. Bureau and Franchet describe a number of new plants from 

 the collections recently brought home by M. Bonvalot and Prince 

 Henry of Orleans, and give a general summary of their character, 

 of which the following is an abstract. The collection was made 

 almost entirely in a narrow band of territory reaching from Lhassa 

 eastward near the 30th parallel of north latitude by way of Batang 

 and Sitang to Tatsienlow, in the province of Szochwan, in west 

 China, from which place their route was defiected at a right angle 

 to Yunnan. Considered in its general aspect, the flora of this 

 region, as shown in the collection, is marked by the stunted form 

 of the shrubs and dwarf character of the herbaceous vegetation. 

 Of the forest trees, Coniferce and others, no specimens were 

 brought. It is characteristically a vegetation of high peaks, where 

 drought and strong winds are the main climatic features. The 



