rOLTTECHNIC ASSOCIATION PROCEEDINGS. 663 



any other part of the world, the tauk-waste of alkali works is giveu 

 to any one who will cart it away. 



ARTESIAN WELLS IN ALGERIA. 



About ten years ago a military corps of French engineers com- 

 menced boring for water in Algeria. With two or three exceptions, 

 every boring has succeeded. In 1865, seventy-five wells were 

 delivering 4,200,000 litres of water per hour. The water is limpid 

 and drinkable, but slightly brackish. The effect of these Avells on 

 the desert is remarkable. Around each is a village with date 

 plantations, and the natives finding themselves in possession of 

 something worth protection, no longer indulge their predaceous 

 propensities, but incline to a life of peace. In the Ouled Rir dis- 

 trict thirty wells have been bored, at a cost of 400,000 francs, which 

 has been paid by a tax on the natives. The shallowest well is about 

 one hundred feet deep, and the deepest nearly six hundred. This 

 district now contains 150,000 date trees, and more than 2,000 

 gardens. Four brigades of borers, well provided with implements, 

 are now making explorations and sinking wells in localities which 

 are likely to yield water. 



CHEIVnCAL CALCULUS. 



Sir Benjamin C. Brodie, Professor of Chemistry in the University 

 of Oxford, has recently delivered a lecture " On the mode of rep- 

 resentation afforded by chemical calculus, as contrasted with the 

 Atomic Theory," in which he assumes as his unit that portion of 

 ponderable matter which, at the melting point of ice, and at a 

 pressure of seven hundred and sixty millimeters of mercury, occu- 

 pies a space of 1,000 centimeters. To denote units of chemical 

 substances, he uses Greek letters as symbols, and in such a manner 

 as to indicate that nitrogen, phosphorous, chlorine, bromine, iodine, 

 and several other so-called elementary substances, are compounds, 

 containing hydrogen in combination with unknown elements. It 

 is claimed that this system shows there are three, and perhaps four, 

 fundamentally distinct classes of elemental bodies; the first may 

 be represented by hydrogen and mercury; the second by oxygen 

 and sulphur; the third by nitrogen and chlorine. The only novelty 

 in this classification is the grouping together of elements of widely 

 differing " atomicity." What advantage may be gained by assum- 

 ing that substances not yet decomposed are compounds, and using 

 symbols of volumetric units as a more mathematical form of 

 expression, the author has not yet satisfactorily shown. 



