3r,H 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



QDecembeb, 



Ml. Ull llie ceimiucLic- J 



1 of 30 in. =761-99 mil 1 

 l>. on the square inch > 

 il. on the centimetre ^ J 



Values of the Constant a, depending on the Measure of Elasticity. 



Fur millimetres of mercury . 

 Eni;lish inches of mercury 

 At.iiospheres of 7GU mil. = 29-9221 



inches = 14-/ lb. on the sq. inch V 



= 1-0333 kil. on the centiraetre^J 

 Atmospheres 



= 14-71 lb. 



= l-036kil. 

 Kiliigrammes on the square centimetre 

 Pounds Avoirdupois on the square inch 



N.B. — All /lie Cons/ants are for common logarithins. 



I have applied similar formulae to the vapours oi alcohol and ether, 

 making use of the ex-periments of Dr. Ure. 



In order to calculate the constants, the following experimental 

 data have heen taken, assuming- that, on Dr. Ure's tliermometers, 

 180° were equal to 100 centigrade degrees. 



Table — Vapours of Alcohol and Ether. 



-7-831247 

 6-426421 



4-9J0433 



4-949300 



4 964659 

 6-117817 



The values of the constants in equation (1.), calculated from 

 these data, are as follows, for inches of mercury and Fahrenheit's 

 scale : — 



Alcohol, specific gravity, 0-813 

 Ether, boiling pohit, 105° F. 

 Ether, boiling point, 104° F. 



6-16620 

 5-33590 

 5-44580 



Log. /3 



33165220 

 3-2034573 

 3-2571312 



Log. 7 



5-7602702 

 5-5119893 

 5-3962160 



Absolute zero 462°-3 below ordinary zero. 



The results of Dr. Ure's experiments on the vapours of turpen- 

 tine and petroleum, are so irregular, and the range of temperatures 

 and pressures through which they extend so limited, that the value 

 of the constant y cannot be determined from them with precision. 

 I have, therefore, endeavoured to represent the elasticities of those 

 two vapours approximately by the first two terms of the formula 

 only, calculating the constants from two experimental data for 

 each fluid. The equation thus obtained, 



Log P = o y, 



is similar in form to that of Professor Roche. 



The data, and the values of the constants, are as follows : — 



Table — Vapours of Turpentine and Petroleum, 



point of water, I have not endeavoured to reduce them to the 

 scale of the air-thermometer, as it is impossible to do so correctly, 

 without knowing the nature of the glass of which the mercurial 

 tliormometer was made. 



I Iiave also endeavoured, by means of the first two terms of the 

 formula, to approximate to the elasticity of the vapour oi ^nercury, 

 as given by the experiments of M. Ilegnault. The following table 

 exhibits the comparative results of observation and experiment. 



Table — Vapour of Mercury. 



Preesures in Millemetrea of Mercury, 

 according tu 



The Formula 

 (of ivvo terms.) 



0-115 



0180 



0-49 



3-49 



10-72 



21-85 



760-00 



M. Regnault*8 

 Experiments. 



0-183 



0-407 



0-56 



3-4 6 



10-72 



22-01 



760-00 



Differences between 



CalculGtion 



and Experiment 



In Millimetres. 



-0-068 

 +0-073 

 —0-07 

 +003 



0-00 

 -0-16 



0-00 



The discrepancies are obviously of the order of errors of observa- 

 tion, and the formula may be considered correct for all tempera- 

 tures below 200° C, and for a short range above that point. From 

 its wanting the third term, however, it will probably be found to 

 deviate slightly from the truth between 200° and 358°; while above 

 the latter point it must not be relied on. 



I have not carried the comparison below 72°, because in that part 

 of the scale the whole pressure becomes of the order of errors oF 

 observation. 



In conclusion, it appears to me that the following proposition, to 

 which I have been led by the theoretical researches referred to at 

 the commencement of this paper, is borne out by all the experi- 

 ments I have quoted, especially by those of greatest accuracy, and 

 may be safely and usefully applied to practice : — 



If the maximum elasticity of any vapour in contact with its liquid 

 he ascertained for three points on the scale of the air-thermometer, then 

 the constants of an equatio7i of the form 



LosP = a-?-l 



may be determined, which equation will give, for that vapour, with an 

 accuracy limited only by the errors of observation, the relation between 

 the temperature (<), measured from tike absolute zero (274-6 centigrade 

 degrees below the freezing point of water), and the maximum elasticity 

 (P), at all temperatures between those three points, and for a consider- 

 able range beyond them. 



Although the temperatures are much higher than the boiling 



RSGISTER OP NE'W PATENTS. 



COMPRESSED FUEL. 



William Buckwell, of the Artificial Granite AVorks, Battersea, 

 Surrey, civil engineer, for '•'■improvements in compressing and solidi- 

 fying fuel materials." — Granted March 38; Enrolled September 28, 

 184.9. 



The improvement consists in compressing fuel material by means 

 of percussion force instead of a continuous pressure. The appa- 

 ratus consists of a ram worked by steam or other poivcr, the size 

 of the ram to be about three tons weight, falling tlirough about 

 4 feet, and making about 50 strokes per minute; and beneath the 

 hammer is placed a mould, in which the blocks are to be formed. 

 The mould contains two blocks, divided from each other by an iron 

 plate; and when the upper of the two blocks is formed and suffi- 

 ciently compressed, the lower one is removed, and the upper one 

 takes its place, which allows anotlier to be formed on the top. 

 The mode of extracting the lower block is as follows: — There is 

 no fixed bottom to the mould, but a loose one is provided, and held 

 in its place by a rod or )irop beneath it, which is attached to a 

 piston witliin a steam cylinder. This loose bottom is held up by a 

 catch while the hammer is in operation; but when the lower block 

 lias to be removed from the mould, the catch is withdrawn, and the 

 next blow of the hammer forces out the block, carrying with it the 

 bottom and piston. Tlie upper block now takes the place of the 

 former, within the lower part of the mould, and another block is 



