The Eclectic and general dispensatory : comprehending a system of pharmacy, materia medica, the formulae of the London, Edinburgh, and Dublin pharmacopoeias, prescriptions of many eminent physicians, and receipts for the most common empirical medicines / collated from the best authorities, by an American physician.

Date:
1827
Catalogue details

Licence: Public Domain Mark

Credit: The Eclectic and general dispensatory : comprehending a system of pharmacy, materia medica, the formulae of the London, Edinburgh, and Dublin pharmacopoeias, prescriptions of many eminent physicians, and receipts for the most common empirical medicines / collated from the best authorities, by an American physician. Source: Wellcome Collection.

Provider: This material has been provided by the Harvey Cushing/John Hay Whitney Medical Library at Yale University, through the Medical Heritage Library. The original may be consulted at the Harvey Cushing/John Hay Whitney Medical Library at Yale University.

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    by the combustion of different substances, when all the circumstances are equal; the estimate being formed from the quantity of ice melted during the burning of one pound of each of the substances.* Substances burnt, 1 lb. Hydrogen - - - - Carburetted hydrogen Olefiant gas - - - - Carbonic oxide - - - Olive oil - - - - - Rape oil - • - - - Wax Tallow Oil of turpentine - - Alcohol Sulphuric sether - - Naphtha - - - - - Phosphorus - - - - Charcoal - - - - - Sulphur - - - - - Camphor Caoutchouc - - - - Oxygen consumed in lbs. 6 4 3.5 0.58 3.5 3.5 3.5 1.5 2.8 1.36 Ice melted in lbs. Lavoisier. Crawford. Dalton. Rumford 295 148 133 100 96.5 480 89 97 69 320 85 88 25 104 104 104 60 58 62 60 40 20 70 42 93.073 124.097 126.242 111.582 67.470 107.027 97.834 From this table it appears that hydrogen gas would form the best fuel, where a high temperature is required. c. Percussion, as far as it applies to solid bodies, is another source of caloric. Smiths, for instance, are in the habit of kindling their fires by means of an iron rod, which is smartly and quickly hammered until it becomes red hot; and sparks are produced by the collision of hard bodies, particularly of flint with steel. This effect appears to arise from condensation, or forcing the inte- gral particles-of the bodies closer together, so as to dislodge the latent caloric they con- tain, and give it out in the form of sensible caloric. The specific gravity of iron is in- creased .052 by being hammered ; and it becomes so hard and brittle that it cannot again be heated by percussion, until it has been exposed for some time to a red heat in the forge. By the collision of flint and steel the oxidizement of the steel is also effected, the sparks being small incandes- cent pieces of oxidized iron. d. Friction is also a source of caloric. It is a well-known fact, that a considerable quantity of free caloric is disengaged when two substances are smartly rubbed togeth- er -, but the real source of the caloric thus evolved, still remains undetermined. e. Finally, mixture, or the chemical union of two substances, in many cases evolves caloric. This always takes place when the density or specific gravity of the mixture is greater than the mean of the substances mixed; as in the mixture of alcohol and water, or of sulphuric acid and water; and much caloric is also evolved when water is thrown upon quicklime, owing to the solidi- fication, of the water when it unites with the lime. The caloric which is evolved in these, and other instances of mixture, is the latent caloric, which is the cause of the flu- idity of the components; for as the com- pound is less fluid, and consequently re- quires the presence of a smaller quantity of combined caloric, the superabundance which the more fluid components contained must be necessarily set free. Such are the sources from which caloric is obtained : combustion is the most impor- tant of these; and the knowledge of the laws by which it is regulated, and the modes of conducting it, is of the first consequence in the practice of pharmacy. (See Furna- ces.) Distribictidn and Effects of free Caloric. From whatever source caloric is obtained, it passes from bodies in which it is accumu- lated in a free state into bodies which con- tain less of it, until both are brought to an equilibrium. The state of a body, with re- gard to its power of producing the differ- ent effects arising from the presence of ca- loric, is termed its temperature. and this depends on the quantity of sensible caloric contained in it. Thus, when a vessel con- taining water is placed on the fire, a quan- tity of caloric passing from the fire into the water, the temperature of the water is rais- ed, or it is made sensibly hotter ; and if the water thus heated be taken from the fire and placed in a cold place, the sensible ca- loric accumulated in it, passes from it into the air and surrounding bodies, until it bc-