Page:The American Cyclopædia (1879) Volume III.djvu/631

 CALONNE CALORIC ENGINE 625 sulphuric acid, is passed through the hot satu- rated solution. Calomel in the form of a deli- cate powder and of a dazzling whiteness is pre- cipitated. The liquid, when saturated with the gas, is digested for a time, and when cooled is filtered from the calomel, which is afterward washed. This process has the advantage that it is easily available for making calomel in small quantities. The calomel of Joseph Jewell of London, sometimes called Howard's, which possesses the highest reputation, is prepared by causing the vapor to come in contact with steam in a large receiver. It is thus entirely washed from corrosive sublimate, at the same time that it is condensed into an impalpable powder. Its extreme fineness appears to give it more activity as a medicine than is possessed by the calomel obtained by levigation and elutriation. Calomel is used in medicine to obtain many of the effects of mercury. It is administered in doses of one to ten or more grains, as a cathartic, being supposed to have a special action upon the liver. This is however not proved, and is doubted by many. In smaller doses more frequently repeated, it produces the constitutional effects of mercury ; and if too long retained, or given to persons possessing a peculiar susceptibility, a single dose may give rise to disagreeable effects. Calomel is render- ed soluble in the intestines by the albuminous secretions, and perhaps partly by the alkaline chlorides. It has been supposed that these salts convert a portion of the protochloride or subchloride (calomel) into the bichloride of mercury (corrosive sublimate) at the tempera- ture of the body ; but experiments have shown that this does not take place, at least out of the body. This conversion may however take place from the action of nitro-muriatic acid, hydrocyanic acid, bitter almonds, or cherry laurel water, and it should therefore not be prescribed with these substances. Calomel is incompatible with alkalies, alkaline earths, al- kaline carbonates, soaps, and hydrosulphates. There are few diseases in which calomel has not been largely employed. Such various views are held in regard to its usefulness that it would be difficult to reconcile them, or even to properly state them within appropriate lim- its. The sedative and alterative actions of calomel, which seem to be something distinct from its specific mercurial effect, are those which seem the most hypothetical. It is safe to say, however, that the use of calomel by the greater part of the medical profession has vastly diminished of late years, probably to the ad- vantage of the community. C1LOME, Charles Alexandra de, a French courtier and minister of state, born at Douai in 1734, died in Paris, Oct. 30, 1802. He studied law, and in 1763 became master of re- quests. In 1768 he was made intendant of Metz; and in 1783, through the influence of the count de Vergennes, secretary for foreign affairs, and of the second brother of the king, the count of Artois, he procured the appoint- ment of comptroller general of finance. In this office he brought about at once a seeming prosperity by the dexterous management of extraordinary resources, the frequent and at first successful negotiation of loans, and the exhaustion of all branches of the revenue. Such a system, the only consequence of which was to increase the deficit at a fearful rate, could not last long, and Calonne in 1786 ad- vised the summoning an assembly of notables. The session opened Feb. 2, 1787; the comp- troller candidly acknowledged that within the last few years the loans had amounted to 1,260,000,000 livres, while the annual deficit had increased to 115,000,000, and declared that the only remedy was to reform altogether the financial system by extending the taxes over the property of the nobles and clergy. Upon these disclosures the king at once dis- missed him from office and exiled him to Lor- raine. He afterward removed to England, where he wrote several memoirs justificative of his administration. He subsequently be- came a most active agent of the French emigres at Coblentz, and an adviser of his protector, the count of Artois. lie ultimately separated from this party, and returned to France, where he died a few weeks afterward. With unques- tionable ability he combined a most extraor- dinary levity of character and manner. His most notable publication was Tableau de V Eu- rope en novembre, 1795 (12mo, London, 1796). CALORIC. See HEAT. CALOKIC ENGINE, a prime mover driven directly by heat, without the intervention of steam. The first advantage of such engines is evidently the absence of steam boilers and the dangers incident to their use ; and a second is the avoidance of the loss connected with the change of heat into motion by the intervention of steam, chiefly due to the great specific heat of water, and the still greater consumption of heat as latent heat in the act of evaporation. This is one of the causes that prevent the best steam engine from giving one tenth of the theoretical mechanical equivalent of the heat produced by the fuel consumed. Thus far, however, the results obtained from caloric en- gines have not answered the high expectations of their inventors and others. There are at present two kinds of such engines in use : first, those worked by the force of expansion of at- mospheric air when heated, and secondly, those worked by the expansion of the products of combustion. Montgolfier in France, the in- ventor of the hot air balloon, was also the first, a century ago, to attempt to apply the expan- sion of heated air as a motive power ; but it was not till 1816 that the invention assumed a practical shape through the labors of Dr. Stir- ling in England, who had then a caloric engine in use to pump water from a quarry, and in 1818 obtained a patent for it. In 1827 a more efficient form of this kind of engine was em- ployed by the Messrs. Stirling of Scotland ; and in the same year Parkinson and Crosby of Lon-