EUEAL ENGINEERING. 787 



considered that mortar of work consistency requires about 1^ times as much 

 water as for normal consistency. 



The conclusions from these tests are as follows: (1) The less water required 

 to produce a mortar of a given consistency the higher will be the strength 

 developed by the sand. (2) The coarser the sand and the higher the silica 

 content, other things being equal, the greater will be the strength developed. 

 (3) In using sands of poor quality loss of strength at early periods can be 

 largely overcome by using a diy concrete. (4) The loss of strength is confined 

 chiefly to short periods, being practically overcome with time. 



General conclusions on waterproofing methods for concrete structures 

 by the committee of the American Society for Testing Materials {Engin. 

 and Contract., JfO {1913), No. 3, pp. 59, 60). — The conclusions deduced from 

 6 years' study of methods of waterproofing concrete are as follows : 



Impermeable concrete may be obtained in the laboratory, but due to careless- 

 ness and inaccuracy of proportioning, mixing, and placing of concrete the 

 reverse is usually true in actual construction. The majority of patented inte- 

 gral compouixds to be added to the cement during mixture have little or no 

 permanent effect and may injure the ultimate strength of the concrete. In 

 general more desirable results are obtained from inert compounds acting 

 mechanically in a void-filling capacity than from active chemical compounds. 

 An effort should be made to secure concrete impermeable in itself and pene- 

 trative void-filling surface washes or coatings should be resorted to only as a 

 corrective measure in case of cracks. Waterproofing compounds can not be 

 relied on to counteract the effect of poor workmanship. 



Denatured alcohol as a decarbonizer and engine cleanser, J. A. Anglada 

 (Gas E twine, 15 (1913), No. 6, pp. 309-3i.?).— Experiments with the use of 

 denatured alcohol as a decarbonizer and cleaning agent for gasoline engines 

 are de.scribed. Several engines containing bad carbon deposits were treated 

 when both warm and cold. The combustion chambers were filled with denatured 

 alcohol which, except in 1 or 2 obstinate cases, so softened the carbon in from 

 6 to 8 hours that it was easily removed and the smaller particles were blown 

 out through the exhaust. It was found that heat is not necessary when using 

 denatured alcohol as a decarbonizer, although it accelerates the action. It was 

 also found that due to its cleansing action denatured alcohol is valuable in 

 detecting imperfectly fitting pistons and piston rings. 



[A steam engine for sun power plants] (Sci. Amer. Sup., 76 {1913), No. 1958, 

 pp. 29-32, figs. 14)- — Inasmuch as the success of a sun power plant for irriga- 

 tion pumping and other power purposes depends largely on the use of an efficient 

 small-power steam engine, using steam practically at atmospheric pressure, the 

 inventor of this system of pumping power development produced in conjunction 

 with another engineer a low-pressure, slow-speed reciprocating steam engine 

 adapted to the particular needs of the sun power plant. The economy claimed 

 to be obtained by this engine is attributed to the combined effect of certain 

 modifications and improvements in construction, which bring about a reduction 

 of losses due to friction, valve and piston leakage, and initial condensation and 

 clearance. 



In further developments of small-power steam engines these modifications 

 were applied to a small high-pressure and a small low-pressure engine having 

 practically the same essential details. The high-pressure engine having a 

 cylinder diameter of 16 in. and an 18 in. stroke was tested, both condensing and 

 noncondensing. and the resulting steam consumption per brake horsepower hour 

 compared very favorably with the results obtained under similar conditions from 

 tests of several compound condensing and noncondensing engines of both higher 

 20793°— 14 7 



