250 



THE POPULAR SCIENCE MONTHLY. 



or spring species, fall ploughing under the 

 trees, which breaks up their fragile cocoons 

 that lie secreted in the soil, and in early 

 spring scraping the trunks of the trees 

 where their eggs are lodged in the crevices 

 of the bark, are recommended. These meas- 

 ures fail with the fall sort, and, in the ab- 

 stract of the paper now before us, nothing 

 is suggested to take their place. 



At the same meeting Prof Riley also 

 presented a paper giving an account of some 

 recent experiments with the grape phyllox- 

 era, undertaken for the purpose of deter- 

 mining when the winged female deposits 

 her eggs. He built a tight gauze house six 

 feet high and four square over a Clinton 

 vine. The house was built so as not to per- 

 mit even so small an insect as the winged 

 phylloxera to get in or out, and the vine 

 was trimmed so that but few branches and 

 leaves remained to be examined. Into this 

 inclosure he brought an abundance of infest- 

 ed roots, and from these obtained a sup- 

 ply of the winged females, confined where he 

 could watch their ways. The result of these 

 observations is that, as has been surmised, 

 the eggs are often laid in crevices on the 

 surface of the ground, but still more often 

 on the leaves, attached generally by one 

 end amid the natural pubescence of the un- 

 der surface ; and, while heretofore all efforts 

 to artificially hatch the progeny from these 

 eggs have failed, Pi'of Riley has this year 

 succeeded in hatching them, and presented 

 a tube filled with living females. 



Condensed Beer. A process for condens- 

 ing beer, recently patented in England, is 

 described as follows in the English Mechan- 

 ic : Beer or stout is taken at any stage of 

 fermentation, though the process is better 

 applied when it is fit for drinking, and evapo- 

 rated in a vacuum-pan until it becomes a 

 thick, viscous fluid. The alcohol and water 

 of course pass off in vapor, which, in turn, 

 is condensed in a receiver, and the alcohol 

 recovered by redistilling the liquid. This 

 alcohol may be mixed again with the con- 

 densed beer. By this process of condensa- 

 tion, the beer is reduced to one-eighth or 

 one-twelfth of its original bulk, and, as the 

 fermentation is suspended by the heat em- 

 ployed, the condensed mixture will keep in 

 any climate for any length of time. The 



process of reconverting the mixture into 

 beer is also a simple one, consisting merely 

 in adding the bulk of water originally ab- 

 stracted, and setting up fermentation again 

 by the use of a small quantity of yeast or 

 other ferment. Within forty-eight hours 

 the beer may be drawn from the tap for use, 

 or bottled in the ordinary way ; or, without 

 using any ferment, the beer may be bottled, 

 and charged with carbonic-acid gas 



Is ConsnmptloD contagions ? Some ex- 

 periments and observations recently made, 

 on the transmission of tuberculosis or 

 phthisis from one animal to another, are 

 worthy of note, as indicating one fruitful 

 source of pulmonary disease. Thus it has 

 been found that when an animal with tu- 

 berculated lungs is made the yoke-fellow of 

 a perfectly healthy animal, and the two are 

 housed and fed together, so as to inhale one 

 another's breath, the one which at first was 

 sound, before long exhibits the symptoms 

 of tuberculosis. Again, Krebs has produced 

 tuberculous by giving animals milk from 

 those which were diseased. In addition to 

 rabbits and Guinea-pigs (which animals are 

 very susceptible to the artificial production 

 of the malady), he accidentally induced the 

 disease in a dog by feeding it with the milk 

 of a cow in the last stage of phthisis. As a 

 result of his observations, he asserts that 

 tubercle virus is present in the milk of 

 phthisical cows, whether they are slightly 

 or gravely affected. On vigorous subjects 

 such milk may produce no injurious effects, 

 but the case is likely to be different with 

 children, and those of enfeebled constitu- 

 tion. Similar effects may result from eating 

 the flesh of animals affected with tubercle, 

 and by inoculation with the virus. Thor- 

 ough cooking of milk and flesh-meat neu- 

 trahzes their injurious action. 



Continuity of the Gnano-Deposits. Are 



guano-deposits of recent formation, or do 

 they date from a geological epoch prior to 

 the present? The latter opinion has been 

 held by many eminent scientific men, among 

 them Humboldt. The observations of Bous- 

 singault, however, go to prove the recent 

 origin of these deposits. One fact, cited by 

 Boussingault in support of this theory, is the 

 existence in the guano of the bodies of birds 



