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THE POPULAR SCIENCE MONTHLY 



ing " quality ; the same property of gel- 

 atiuizing is possessed in fruits by pectiue, 

 which is, however, a distinct substance. 

 The stimulating properties of tea and coffee 

 are due to their peculiar alkaloids, theine 

 and caffeine ; their flavor, to aromatic sub- 

 stances which are extracted by the hot water 

 from the leaf or berry. Wheat-flour is 

 composed of starch with gluten, and more 

 or less of mineral or inorganic substances. 

 The finer and whiter flours are nearly pure 

 starch, and are not so nutritious as the less 

 attractive brown flours. The raising of 

 dough is a true process of fermentation, 

 precisely similar to that of the brewer or 

 distiller, but the alcohol soon passes away. 

 Sugar, when heated, melts, and is converted 

 into an uncrystallized, pliant mass, known 

 as barley-sugar, or sugar-candy. At a some- 

 what higher temperature it is decomposed, 

 and a dark-brown substance, known as car- 

 amel, is formed. Granulated sugar is sel- 

 dom adulterated. The term salt, in its 

 technical sense, includes the fats, which are 

 compounds of characteristic acids with gly- 

 cerin as a base. Upon adding potash or 

 soda, the acid combines with the alkali, 

 forming soap, and the glycerin is set free. 

 If soda is used, hard soap, if potash, soft 

 soap, is formed. 



Purification of Sewage by Infiltration. 



— Filtration of sewage is defined in the re- 

 port of the Royal Commission on Metropoli- 

 tan Sewage Discharge to be its concentra- 

 tion, at short intervals, on an area of specially 

 chosen porous ground, as small as will ab- 

 sorb and cleanse it ; not excluding vegeta- 

 tion-culture, but making the produce of 

 secondary importance. On a suitable soil, 

 such as a sandy loam with a small propor- 

 tion of gritty gravel, specially prepared by 

 surface leveling and deep under-drainage, 

 one acre is said to be capable of purifying 

 the sewage of one thousand people, manu- 

 facturers' refuse and storm and surface 

 waters excluded. Mr. Bailey Denton, who 

 has had ten years' experience in filtration, 

 and has published a book about it, does not 

 think it necessary, or even, in most cases, 

 desirable, to precipitate the sludge before 

 applying the sewage to the filtration-beds. 

 He does not believe that under proper treat- 

 ment sludge is capable of clogging the pores 



of the land or of injuring vegetation. He 

 advises the laying out of the filtration-beds 

 in ridges and furrows, the sewage only to 

 flow into the furrows and not to be allowed 

 to flood the ridges on which plants and vege- 

 tables are growing. As soon as the deposit 

 of sludge on the sides of the furrows is suSi- 

 cient to prevent infiltration in any great de- 

 gree, the sewage should be withheld from the 

 areas so affected. The sludge should then 

 be allowed to dry partially in the furrows, 

 and when in a fit condition be lifted and dug 

 into the ridges. The slimy matter, which 

 has appeared so considerable and which 

 puddled the bottom of the furrows when 

 wet, shrinks to a skin of very insignificant 

 thickness when dry, and is readily broken 

 up and mixed with the soil. The inter- 

 mittency of the application of the sewage 

 to the filter-beds is essential. Each bed 

 should have eighteen hours' rest out of the 

 twenty-four, to allow air to follow the pores 

 of the land, and thereby renew the oxidiz- 

 ing properties of the soil. The assimilative 

 power of growing plants is doubtless also a 

 great aid in the purification of sewage. In- 

 termittent filtration is probably, however, 

 likely to have its most useful application in 

 combination with surface or broad irrigation. 



Tlie Slavic Feast of St. Jficliolas.— The 



feast of St. Nicholas takes the place, among 

 some of the Slavic peoples, of our Christmas. 

 The chief featui-e of the festival is the cate- 

 chization of the children on the eve of the 

 day, for which the good bishop is personated 

 by a youth dressed in long white vestments, 

 with a silk scarf, and furnished with miter 

 and crosier. He is accompanied by two 

 angels, also suitably dressed, and followed 

 by a troop of devils, having blackened vis- 

 ages, horns, pigs' faces, and other ingen- 

 iously devised distortions, and all rattling 

 chains. The visitations take place at the 

 houses where the children are gathered in 

 their evening parties. St. Nicholas enters 

 with two angels, while the devils are left 

 outside. He calls up the children one by 

 one, and seriously examines them, with 

 questions suited to their ages, and in their 

 knowledge of prayers and hymns. Those 

 who pass the questioning successfully are 

 rewarded with presents of nuts and apples ; 

 those who fail have to stand aside. After 



