532 Chronicles of Science. [Oct., 



to keep fatty substances from becoming rancid, while it may use- 

 fully serve in laboratories to wrap up caustic lime, bisulphite of 

 soda, and similar substances, which may thus be preserved for a 

 great length of time without deterioration. 



The cause of the precipitation of muddy matter from water by 

 the aid of dilute saline solutions has been investigated by Dr. Ch. 

 Schlasing. Water otherwise pure, but contaminated simply with 

 clay (as may be the case with the water of rivers after heavy rain 

 or fall of snow), becomes at once clarified by very minute quantities 

 of some salts of lime : 10 1 00 th part of chloride of calcium for 1 part 

 of water effects this purpose in a moment ; the nitrate, bicarbonate, 

 and caustic lime act in the same manner. The precipitated sub- 

 stance may be readily separated from the water by filtration, 

 whereas the filtration of the water containing the suspended matter 

 is very difficult, because the pores of the niters become choked. The 

 practical importance of this matter is very great, since it is, for 

 instance, a well-known fact that the water of some rivers (the 

 Durance being notorious in this respect) does not, in winter time, 

 and after heavy rainfall or snow-storms, become quite clear, even if 

 left at rest in large ponds for a considerable time. The same is the 

 case with the water of the Ehine, which in its lower course is often 

 turbid for weeks together, simply from the effects of very finely- 

 divided clay being suspended even after the water has been at rest 

 in tanks. The water of the river Durance supplies Marseilles with 

 fresh water, the latter being brought to that city by a magnificent 

 series of works, among which may be mentioned the celebrated 

 Aqueduc de Koquefavour. Certain bitter vegetable substances have 

 been applied both in Egypt and in India, for the purpose of ren- 

 dering the waters of the Nile, Ganges, Indus, and other large rivers, 

 potable, many centuries before the rationale of the action of these 

 substances was understood. 



6. ENGINEEBING— CIVIL AND MECHANICAL. 



The Mitrailleur. — Unfortunately the peaceful progress of Engineer- 

 ing Science has, within the last few weeks, been suddenly inter- 

 rupted by the outbreak of hostilities on the Continent; and 

 prominence has consequently, for the time, been obtained by that 

 branch of engineering which devotes its energies to the production 

 of warlike engines and materials. For some years past attention 

 has been given to the improvement of our artillery, and the revival 

 of breech-loading cannon, which for a while was received with much 

 favour, is already beginning to find strong opponents from the fact 

 that, as a rule, they possess less precision than the old muzzle- 



