INDUSTRIAL PROGRESS DURING THE YEAR 1875. xlvii 



of equilibrium is regulated by one superior and two lateral 

 balls. If now the cylinder be filled with water, it remains 

 perpendicular; but on opening the orifice at the bottom the 

 water pressure is relieved on that side, and the cylinder 

 swings in the opposite direction. The apparatus may be 

 made to show also the change in the form of the parabola as 

 the height of the water column decreases. 



Paquet has described a new densimeter, w T hich is simply 

 the instrument of Rousseau modified so that it can be used 

 for solids. An ordinary hydrometer has an enlargement 

 upon the top of the stem about half a square centimeter in 

 section and fifteen centimeters long, closed at the lower end, 

 and divided into cubic centimeters and tenths. A zero point 

 is marked at the level of the second centimeter mark, and 

 the instrument is so weighted that when the upper tube is 

 filled with water to the zero level, it sinks in water to the 

 bottom of the stem. To the water in the upper tube a def- 

 inite weight, the maximum ever to be needed, is added say, 

 six grammes. The instrument sinks to a certain point, which 

 is noted on the stem and marked 60, and the stem is divid- 

 ed between this mark and zero into sixty equal parts, the di- 

 visions being continued up if there is space. Each division 

 corresponds to one decigramme. To use the instrument, two 

 cubic centimeters of water are placed in the upper tube, and 

 the whole immersed in water, sinking to zero. The fragment 

 of mineral, for example, to be determined is placed in the 

 water in the upper tube, and thereby raises its level three 

 divisions ; the volume of the fragment is therefore 3 c. c. 

 The instrument sinks by the increased weight, say, to the 

 fifty-fifth division ; hence its weight is 55 decigrammes or 5.5 

 grammes. The specific gravity is 5.5-7-3, or 1.83, therefore. 



Arzberger and Zulkowski have proposed a new form of 

 water air-pump, founded on the principle of the increased flow 

 of liquids caused by an ajutage like an inverted fru strum of 

 a cone. By a lateral opening, water, under considerable 

 pressure, enters a small cylindrical box, upon the top of 

 which is the air tube, entering about half-way, and narrow- 

 ing to a point. This enters and opens into the narrow end 

 of a slightly conical tube called the diffuser, which projects 

 several inches below the box, and by which the water issues. 

 The supply of water must keep the tube full, and as it wid- 



