Hess (18 4 o) were the first who systematically investigated thermochemical effects in solution, and arrived at conclusions from their experimental data which still possess validity.
Hess, from his work, arrived at the converse conclusion, that when a series of bases were used to neutralize a given amount of an acid, the heat of neutralization was always the same.
This affords an example of a principle which had been stated by Hess in a very general form under the name of the Law of Constant Heat Sums - namely, that the thermal effect of a given chemical action is the same, independently of the character and number of the stages in which it takes place.
Hess also stated another principle on empirical grounds, which, although admitting of many exceptions, is of considerable utility and significance.
Hess now observed that in the process of mixing such neutral solutions no thermal effect was produced - that is, neutral salts in aqueous solution could apparently interchange their radicals without evolution or absorption of heat.
After the investigations of Hess and Andrews, a great deal of excellent experimental work was performed by P. A.
This deduction harmonized the observations of Andrews and of Hess previously alluded to, and also accounted satisfactorily for the Law of Thermoneutrality.
It is adorned with a cycle of religious paintings by Heinrich von Hess (1798-1863), and the dome is supported by sixtyfour monoliths of grey Tyrolese marble.
Hess, Der Hochtourist in den Ostalpen, 3rd ed., 3 vols.
Hess, who showed that acetone will absorb twenty-five times its own volume of acetylene at a temperature of 15° C. under atmospheric pressure, and that, providing the temperature is kept constant, the liquid acetone will go on absorbing acetylene at the rate of twentyfive times its own volume for every atmosphere of pressure to which the gas is subjected.
Hess, Der Hochtourist in den Ostalpen (2 vols., 18 94, 3 vols., 3rd ed., 1903); the 3 vols.
See Vogler, Ems, seine Heilquellen, Kureinrichtungen, &c. (Ems, 1888); and Hess, Zur Geschichte der Stadt Ems (Ems, 1895).
The following are some of the values deduced by well-known experimentalists for the latent heat of fusion: - Regnault, 79.06 to 79.24 calories, corrected by Person to 79.43; Person, 79.99 calories; Hess, 80.34 calories; Bunsen, 80.025 calories.
Regnault, Person and Hess employed the method of mixture which is probably the most accurate for the purpose.
Person and Hess avoided the error of water sticking to the ice by using dry ice at various temperatures below o° C., and determining the specific heat of ice as well as the latent heat of fusion.
Hess in 1840) does not warrant the conclusion that he realized the existence of any law of invariable and reciprocal proportions in the combinations of acids and bases.