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POPULAR SCIENCE MONTHLY. 



to regulate the supply in a hygienic way by 

 control of its sources. For this reason some 

 general method of purification, which can be 

 applied to the milk in bulk after it has been 

 collected, becomes an essential to a safe 

 product for general consumption. The ordi- 

 nary tests, while fairly accurate in deter- 

 mining adulteration, are of no value in indi- 

 cating the presence of disease germs or 

 ordinary dirt. In fact, nearly any sample 

 taken from the milk wagons of a city will be 

 found to contain a number of bacilli which 

 would immediately condemn any water as 

 unfit for drinking. Sand filtration has been 

 practiced for several years in some Conti- 

 nental cities, and apparently with very satis- 

 factory results. The filters used by Messrs. 

 Boll, large milk dealers of Berlin, consist of 

 cylindrical vessels divided by horizontal per- 

 forated diaphragms into five superposed 

 compartments, of which the middle three are 

 filled with fine, clean sand, sifted into three 

 sizes, the coarsest being put into the lowest 

 and the finest into the uppermost of the 

 three chambers. The milk enters the low- 

 est compartment, and, having traversed the 

 layers of sand from below upward, is carried 

 by an overflow to a cooler fed with ice water, 

 whence it passes into a cistern, from which 

 it is drawn direct into the locked cans for 

 distribution. The filtered milk is not only 

 freed from dirt, but the number of bacteria 

 is reduced to about one third, without steril- 

 izing. The loss of fat is, in new milk, stated 

 to be small, but the quantity of mucus and 

 slimy matter retained in the sand — which is, 

 of course, renewed every time — is surprising. 



Spirit Drinking and Mental Depression. 



— Facts brought out by Mr. Bateman, of the 

 British Board of Trade, in reference to the 

 amount of drinking in different countries 

 make the people of the United Kingdom more 

 moderate in their drinking habits than has 

 generally been supposed, and place them 

 among the more temperate nations ; for while 

 in the consumption of beer, SO.T gallons a 

 head, they exceed the Germans as a whole 

 with 25.5 gallons a head, the relatively small 

 quantity of wine drunk, less than half a gallon 

 per head, as against 29.50 gallons in France 

 and the adjoining countries, more than re- 

 stores the balance. And this result is not 

 changed when the stronger drinks than wine 



are taken into consideration — 1.9 i gallons per 

 head in Germany, 1.85 in France, and 1.01 in 

 the United Kingdom. The Bavarians are the 

 greatest beer drinkers, consuming an average 

 of fifty gallons each in a year ; next to them 

 are the Belgians, with 43 gallons. The United 

 States appears in the table as a vastly more 

 temperate nation than any of these, its aver- 

 age rate of consumption of beer, wine, and 

 spirits being less than half that of Great 

 Britain. The London Spectator, taking Mr. 

 Bateman's tables as its text, tries to find a 

 mental rather than a physical cause for the 

 appetite for drinking, and discovers it in 

 the use of spirits as a means of obtaining 

 relief from depression. In the United States, 

 where the cUmate is exhilarating, life is easy, 

 and the people are satisfied, drinking is de- 

 creasing ; while " it is in France that drink- 

 ing is now most prevalent, and is assuming 

 the form least connected with the actual en- 

 joyment of fermented liquor." Though wine 

 is plenty and all are trained from childhood 

 to drink it, the people " are taking to strong 

 spirits of peculiarly nasty flavors," and some 

 are spending nearly half their wages upon 

 them. This, it thinks, is because " in France 

 more than in any other country the people 

 are becoming depressed and pessimistic, part- 

 ly through the general loss of their faith, 

 partly through a consciousness that they are 

 not as great in the world as they think they 

 ought to be, partly through the rise of the 

 savage pecuniary discontents which produce 

 what we are accustomed to call socialism." 



Insects, and Books abont them.— In a 



Brief Historical Survey of the Science of 

 Entomology, by C. L. Marlatt, president of 

 the Entomological Society of Washington, 

 an estimate is made of the extent of ento- 

 mological literature. Hajen's Bibliotheca, 

 in 1862, listed 4,766 authors, 18,130 dis- 

 tinct titles, and 851 anonymous publications. 

 The last volume of the Zoological Record, for 

 1895, gives 1,251 titles of publications on 

 insects, which might perhaps be equivalent 

 to seventy-five 500-page volumes ; and Mr. 

 Marlatt supposes, as a very conservative 

 estimate, that what would amount to 2,000 

 such volumes have been published since the 

 date of Hajen's work. In economic ento- 

 mology, Henshaw's Bibliography of 1888 

 contains 5,424 titles and the names of more 



