Pebruary I, 1889.] 



SCIENCE. 



75 



Purifying Company of New York liave in their apparatus com- 

 bined many, if not all, of these requirements ; and an extensive 

 plant installed by them at Chattanooga, Tenn., gives conclusive 

 proof that scientific principles have entered into the construction 

 ■of the plant, which seems to have well stood the crucial test of 

 actual practice. The rapidity and thoroughness with which these 

 filters can be cleaned, and the small expenditure of water required, 

 are qualities in which this company excels, as they seem to have 

 ■effectually solved the vexed question of surface washing. It has 

 been found, from long experience, that most of the impurities taken 

 from water, in the course of twenty-four hours lodge in the upper 



in the boiler, necessitates a periodical stopping for its removal, 

 ceases to be troublesome. It has been demonstrated beyond 

 question that the thorough purification of drinking-water can be 

 accomplished by combining aeration, precipitation, and filtration ; 

 and it is also reasonably claimed that the thorough aeration of 

 water under pressure has the effect of destroying bacteria and 

 plant-life that would be injurious to health. The aeration is ac- 

 complished by means of an air-compressor, whereby air is forced 

 into the water under high pressure, thus producing a chemical 

 action, which destroys the disease germs in the water, making it 

 clear and sparkling. The process employed to attain this end by 



OF NATIONAL FILTER (25O 



six to ten inches of the sand-bed through which the water must 

 pass before it leaves the filters, and that in their large machines, 

 having a capacity of 250 gallons per minute of pure filtered water, 

 this surface washing can be accomplished in four minutes, after 

 which a reverse current up through the sand-bed breaks it up com- 

 pletely, and throws out all the finer particles of dirt. As the only 

 labor required to accomplish this cleansing is the mere opening 

 and closing of valves, the reverse current doing all the work, some 

 idea of the extreme simplicity of the filter can be formed. By 

 creating a feed of water free from those impurities which induce 

 the formation of " scale " in boilers, a great economy of " fuel " is 

 effected ; the salts and other deleterious substances being deposited 

 in the sand-bed of the filter, instead of passing into the boiler and 

 shortening its period of usefulness by hastening corrosion, while 

 the sediment that induces foaming, and which, gradually settling 



the National Water Purifying Company is simple and inexpensive, 

 and by it the amount of air forced into the water can be regulated 

 to the exact requirements of the case. As a result, all odor in the 

 mains, and vegetable growth, such as algse, in the reservoirs, are 

 prevented. 



THE CULTIVATION AND UTILIZATION OF RAMIE 

 IN THE UNITED STATES OF AMERICA. 



In his recent report on the Brussels Exhibition, Mr. Joseph 

 Zervas draws attention to the importance ol the cultivation of 

 ramie. During the last thirty years, he says, numerous experi- 

 ments have been made with a view to finding new plants yielding 

 textile fibres. One of the most promising among these is the 

 ramie, which is obtained from two plants, — Bohmeria ttivea, yield- 



