May 25, 1883.1 



KNOWLEDGE ♦ 



509 



vapour — no more can be forced into it without raising its 

 temperature. 



But while thus charged with aqueous vapour, tliere 

 would still be room for \apour of alcohol, or turpentine, or 

 ether, or chloroform, itc. It would be a vacuum to these, 

 though a plenum to itself. On the other hand, if the 

 alcohol, turpentine, ether, or chloroforu\ were allowed to 

 evaporate into the bell-glass, a certain quantity of either 

 of these vapours would presently enter it, and then this 

 vapour would act like a solid mass in resisting the entry 

 of any more of its own kind, wliile it would be freelj' per- 

 vious to the vapour of water or that of the other liquids. 



A practical example will further illustrate this. Some 

 years ago I was engaged in the distillation of parallin oil, 

 and had a few thousand gallons of the crude liquid in a 

 still with a tall head and a rising condenser. In spite of 

 severe firing, the distillation proceeded \»'ry slowly. Then 

 I threw into the still, just above the surface of the oil, a 

 jet of steam. The rate of distillation immediately increased 

 with the same firing, although the steam was of much 

 lower temperature than the boiling oil, and, therefore, 

 wasted much heat. The rationale of this was that at first 

 an atmosphere of oil vapour stood over the oil, and this was 

 impervious to more oil vapour, but on sweeping this out 

 ■and replacing it by steam, the atmosphere above the liquid 

 ■oil was permeable by oil vapour. This principle is largely 

 applied in similar distillations. 



But I am exceeding my limits, and must, therefore, defer 

 the direct application of these principles to my next, 

 though, doubtless, most of my readers will anticipate, or in 

 vulgar but expressive phrase, " see what I am driving at." 



Ix a paper in the Comptes Rendus, " On the Liquefaction 

 -of ICitrogen," by MM. Wroblewski and Olszewski, it is 

 stated that nitrogen cooled in a glass tube to — 136° C, 

 -and under a pressure of 150 atm., does not liquefy. On 

 sudden release there is tumultuous eVmllition. Gradual 

 release, not passing 50 atm., yields the liquid, clear and 

 ■colourless, with a distinct meniscus ; it evaporates very 

 •quickly. The liquefaction of CO under like conditions on 

 April 2lst was announced. 



Lake Wissipeg. — Recent exploration and levelling 

 shows that the surmise of General G. K. A\'arren to the 

 effect that Lake Winnipeg once discharged itself into the 

 Mississippi on the south, instead of Hudson's Bay on the 

 ■east, is correct. Mr. J. D. Dana, the well-known geo- 

 logist, in a paper in the ^l /iii;rir.an Journal of ^Science, fully 

 •discusses the evidence, and shows that the change was due, 

 not to a barrier of ice or earth, but to a change of level 

 over a wid^e area. The geological facts he adduces point to 

 the following succession of events : The lake deposits, 

 being underlaid by unstratified drift, show that before 

 the great lake existed, a glacier had moved south- 

 waixl over that region, and deposited moranic mate- 

 rial, The high level prairie on either side of the 

 iake region and of the Minnesota A' alley is made up of 

 this unstratified drift ; but the generally level surface in 

 the part next the lake valley and the stratification in the 

 material show that the floods from the melting ice levelled 

 it. This period of floods was followed by the era of the 

 great lake, that is to say, of quiet waters and gentle deposits, 

 w-ith a slow discharge over the Lake Traverse region, 

 which appears to have been brought about by a diminu- 

 tion in the slope of the general surface, which was part of 

 a great change of slope which went on, as General Warren 

 iias explained, until the land was reduced to its present 

 inclination and the stream to its present courses. 



BALDNESS. 



IN an article recently contributed to the Gcsrindheit — - 

 a paper, as its name imports, devoted to sanitary 

 subjects — ProfessorReclam, aGermon OVA/; ;-/';r, makes some 

 timely and useful observations on the subject of baldness. 

 After describing, in a vein of pleasantry, the vast array of 

 bare polls which may be seen any evening in the pit of a 

 theatre or the body of a lecture-room, he discusses the 

 causes of baldness. He does not think, as is sometimes 

 said, that loss of hair is the result either of impaired 

 health or of much study. The strongest men are often bare- 

 headed, and German professors, who are nothing if not 

 studious, arc distinguished above all men by the pro- 

 fusion of their locks. On the other hand, soldiers and 

 postilions, who wear heavy helmets and leather caps, and 

 wear them a good deal, are frequently as bald as billiard- 

 balls. From these facts Herr Reclam draws the con- 

 clusion that Ijaklness comes chiefly of the artificial 

 determination of blood to the head, and to the heat and 

 perspiration thence arising. The result is a relaxed con- 

 dition of the scalp and loss of hair. If the skin of the head 

 be kept in a healthy state, contends the Professor, the hair 

 will not fall oil'. To keep it healthy, the head-covering 

 should be light and porous, the head kept clean by wash- 

 ings with water, and the hair cut short. The nostrums 

 vended as hair restorers, and on which a fabulous amount 

 of money is wasted by the ignorant for the benefit of 

 quacks, he denounced as worse than useless. In ninety-nine 

 cases out of a hundred they are worse than useless. Cleanli- 

 ness and cold water are the sole trustworthy specifics ; but 

 when once the hair roots are destroyed, not all the oil of 

 Macassar, the bear's grease of Siberia, nor the cantharides 

 of Spain will woo back the vanished locks. 



The census of 1 880 shows that the unsettled area of the 

 United States amounted to 1,400,000 .=quare miles, being 

 nearly one-half the entire area of the country. The 

 unsettled area east of the Appalachian range of mountains 

 has been reduced to 10,000 square miles only, and in the 

 original thirteen states there are less than 15,000 square 

 miles unoccupied. Wisconsin and Michigan show 20,500 

 -square miles as still unsettled, while Texas has no less than 

 137,000 square miles of vacant land. In the territory west 

 of the Mississippi, including Minnesota, Dakota, Kansas, 

 Nebraska, Iowa, Missouri, Arkansas, New Mexico, Arizona, 

 Colorado, Montano, Idaho, and the Pacific States, 1,200,000 

 square miles are either unoccupied or inhabited only by 

 Indians. There is thus room for an enormous increase of 

 population. 



A coitRESPONDEXCE is proceeding in the Giornal dei 

 Lnvori J'ubblici (Rome, JMay 9) on the question of 

 constructing a steel bridge over the Strait of Messina. 

 Engineer Giambastiani has presented to the Minister of 

 Public Works a plan for the colossal bridge, to be liuilt in 

 five spans, three of which would measure one kilometre 

 (021 of a mile) each. This design has been favourably 

 received by Signor Baccarini. Engineer A. Cokran (of 

 the Imprefa Induiytriah') now writes to point out that he 

 had himself prepared a plan for such an enterprise as far 

 back as the year 18G6, and that it is perfectly practicable, 

 if the cost can be met. The question of foundations 

 presents the chief difficulty, on account of the great depth 

 of the Straits (about 196 ft. being the minimum), and this 

 he suggests meeting Viy founding the piers of the bridge 

 upon submerged pontoons, anchored at a depth of about 

 35 ft. below the surface. He appears to doubt, however, 

 whether the enormous cost of the undertaking would be 

 worth incurring. 



