NATURAL PHILOSOPHY. 205 



observations ; when the temperature had to be carried above 600, a 

 funnel only eighteen inches long was used. The state of the liquid in 

 the tube was closely examined by means of a watchmaker's lens, and 

 could at all times be seen distinctly by transmitted light. One set of 

 tubes were of hard Bohemian glass, one-eighth of an inch bore, and 

 one-fiftieth of an inch thick. These sometimes burst when the pres- 

 sure was calculated to be about 400 atmospheres, if the laws of density 

 and pressure hold good at these extreme points. The force of the ex- 

 plosion was quite what might be anticipated : it was as if the liquid, 

 which never exceeded three grains in weight, had been fulminating 

 powder. The thick glass funnel was shattered into small fragments 

 immediately opposite the tube. Other sets of tubes were of soft glass, 

 one-twentieth of an inch thick, and one-fifth or one-sixth of an inch 

 bore. None of these burst ; at a very high pressure, one merely gave 

 way, breaking across into three pieces as if cut by a file. The author 

 then gave the details of his experiments in a tabulated form, each not- 

 ing the low temperature and volume, the maximum volume and tem- 

 perature, and the transition volume and temperature, with notes of 

 the successive appearances noted in the liquid at its surface and in the 

 vapor. The surface of the liquid at one stage always assumed a flat 

 form, showing cessation of capillarity often assumed a conoidal form 

 wasting at the apex ; sometimes two surfaces showed themselves. The 

 conversion currents seen clearly in the early stages, often changing 

 into zigzag motions of spherules of vapor at the transition point. In 

 this way the author examined sulphuric ether, alcohol, sulpheret of 

 carbon, distilled water, chloroform, dichloride of sulphur, anhydrous 

 oil of turpentine, acetic acid, and sulphuric acid. 



EVAPORATING POWER OF VARIOUS BOILERS. 



The following interesting table of the work performed by boilers of 

 different constructions in this country and England was furnished by 

 Dr. S. B. Dana, of the Merrimack Works, Lowell. The article was 

 called forth by the publication of a statement in regard to Baker's Im- 

 proved Furnace, in which it was stated that, for the week ending Oct. 

 29th, the steam boiler at the Crystal Palace in New York, heated by 

 Baker's furnace, evaporated 11.45 pounds of water with one pound of 

 coal. We are not informed of the temperature from which the water 

 was evaporated. This is a material point. It is, however, evident 

 that the temperature has been reduced to the usual common standard 

 212 F., for it is said in the notice above, the obtained result "comes 

 within three pounds of the theoretical evaporation of water by the best 

 quality of coal, in the Laboratory." 



Despritz experimentally determined that one pound of pure char- 

 coal from sugar, would evaporate 12.3 pounds of water from 32 F.; 

 Dr. Schafhaeutl, from theoretical calculations, assumes that one 

 pound of anthracite coal, containing 92.42 per cent, carbon, and 3.37 

 hydrogen will also evaporate 12.3 pounds of water from 32. Reduo 

 ing this to to 212, we arrive at the fact that one pound of pure char- 



