The thermal effects increase as one passes from primary to tertiary alcohols, the values deduced from propyl and isopropyl alcohols and trimethyl carbinol being: - primary =45 08, secondary = 50.39, tertiary = 60.98.
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.
Electric-radiative circuits like thermal radiators are divided into two broad classes, good radiators and bad radiators.
The rail-failures mentioned above also drew renewed attention to the importance of the thermal treatment of the steel from the time of melting to the last passage through the rolling mill and to the necessity of the finishing temperature being sufficiently low if the product is to be fine grained, homogeneous and tough; and to permit of this requirement being met there was a tendency to increase the thickness of the metal in the web and flanges of the rails.
(i) Generally speaking, there is a considerable thermal effect when a substance is dissolved in water, and this effect varies in magnitude according to the amount of water employed.
The notation which Julius Thomsen employed to express his thermochemical measurements is still extensively used, and is as follows: - The chemical symbols of the reacting substances are written in juxtaposition and separated by commas; the whole is then enclosed in brackets and connected by the sign of equality to the number expressing the thermal effect of the action.
The chemical characters of the well-waters, the irregular distribution of the water-pressure, the distribution of the underground thermal gradients, and the occurrence in some of the wells of a tidal rise and fall of a varying period, are facts which are not explained on the simple hydrostatic theory.
- One pound of good Welsh coal properly burned in the fire-box of a locomotive yields about 15,000 British thermal units of heat at a temperature high enough to enable from 50 to 80% to flow across the boiler-heating surface to the water, the rest escaping up the chimney with the furnace gases.
The thermal efficiency is therefore 185/1013 =0.183.
When the initial pressure is 100 lb per square inch by the gauge the thermal efficiency drops to about nearly 15% with the same back pressure.
22 represents the thermal efficiency actually obtained in one of Adams and Pettigrew's experiments, namely, 0-I I, the pressure in the steam-pipe being 167 lb per square inch.
For further information regarding the standard engine of comparison see the article Steam Engine and also the " Report of the Committee on the Thermal Efficiency of Steam Engines," Proc. Inst.
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.
The total thermal effect, too, which is associated with the transformation, must be the same, whether the transformation is conducted directly or indirectly (Hess's Law of Constant Heat Sums), since the thermal effect depends only on the intrinsic energies of the initial and final systems.
In 1901 the Copley medal of the Royal Society of London was awarded him as being "the first to apply the second law of thermodynamics to the exhaustive discussion of the relation between chemical, electrical and thermal energy and capacity for external work."
By experiment it is found that the thermal effect of a double bond is much less than the effect of two single bonds, while a triple bond has a much smaller effect than three single bonds.
Zinc with solutions of copper salts), the thermal effect is practically independent of the nature of the acid radical in the salt employed.
When thermal units are employed.