n * /*" LECTURES ON CHEMISTRY, DELIVERED IN THE COLLEGE OF PHYSICIANS AND SURGEONS TNIVERSITY OF THE STATE OF NEW-YORK PRINTED. BY A. MING, 84 FRONT STREET 1828. OUT LINES OF THE Lectures on Chemistry FIRST DIVISION OF THE COURSE. GENERAL PROPERTIES OF MATER ; E mbracing a statement of the laws relating to those agents or forces concerned in the production of chemical which are phenomena. 1. ATTRACTION., A. Remote—or Gravitation. B. Contiguous—subdivided into two kinds: Cokesion and Affinity. 1. cohesion. Acts as antagonist force to caloric. Degree* of thisproperty in different bodies. Effects of temperature. Action of liquids- Methods of overcoming the cohesion of bodies. 1 By heat. 2 By mechanical power. 3 By the agency of affinity. Production of crystalline forms. 1 By cooling from «) The capacity for heat exhibited by different bodies is very unequal. Methods of determining the capacity of solids, liquids and gases. Specific heat, means the relative capacities of different bo- die?, compared with some standard. The standard for solids and liquids is water, and for aeriform bodies, common air. The capacity of a body is altered by a change in its den- sity ; thus compressing: air diseneaeres caloric : but when it is rarified, there is an absorption of heat in consequence of an enlargement of capacity. Formation of clouds explained. The absolute quantity of heat which any body contains is unknown. Discordant calculations on this sbject. STEAM AND VAPOUR. Bodies in passing: from a liquid to an aeriform state absorb a vast quantity of heat. The boiling: of a liquid is caused by the rapid formation and escape of vapour. The production of vapour in smaller quantities and proportionate to the temperature takes place before ebullition commences. The relative volumes occupied by the same substance in the solid or liquid, state, and in the form of gas, are very different.' Steam, at the pressure of the atmosphere, is more than 1HH) rarer than water- The boilingr point of even' liquid is invariable while thr 10 pressure remains the same ; but is lowered when the pressure is reduced. Influence of altitude on the boiling of liquids. In vacuo ebullition takes place at 120° F. less temperature than in the open air. On the contrary, increasing: the pressure, raises the boiling point. In a strong: vessel, water may be heated red hot with- out boiling. Papins's digester. Perkin's steam-gun. The elasticity ot steam increases in a constant ratio with the temperature, i e- it is double! tor every 40°F Capacity, of latent heat ot ste im : how determined. Production of cold by rapid evaporation, caused by the larg^ quui'iiy ot'caioric absorbed by the vapour. Freezing of water by evaporating ether on its surface. Ot" t le steafii c-ii^ine. ^avarv's ju 1 N'ewcomcn's i ti^i.ies Mr. -V'att's i.iijjioveiiientii. iJigti pressure engines. Equal wei^h of straui contains me same qjantity of calo- ric : us latent heat diuiinisuiig as it* -eu>iL>,e tieat increases. Evaporation in vacuo is uciiitated by th- ab^orbii.^ power of sulpnuric acid or otner materials. Mi. LesJie's m<;tuod of freezing water. lnlueuce or evaporation or insensible perspiration, on the temperature ot living aniaiais. Persons may endure, with little inconvenience, air htvted far above the boiling point of water, il their bodies perspire freely. 11 Manner of cooling liquids by evaporation. Explanation of the cryophorusolDx. Wollaston, and of the pnlse glass. Distillation. Different vessels for performing this opera- tion described. Distillation in vacuo. Ignition or incandescence. The temperature at which soiid bodies become red hot is probably about 810°F. Air cannot be heated so as to be- come luminous, except when it is in the state of flame. The luminousness ot heated bodies is not satislactorily accounted for. SOURCES OF HEAT." 1 The solar r3ys. 2 Electricity. 3 Mechanical action. 4 Chemical action. 5 Vital action. ELECTRICITY. General remarks Electrical phenomena observed when glass, sealing wax, &c. are subjected to iriction. 1 Attraction and repulsion 2 Peculiar sensation. 3 Noise. 4 Light. t Division of bodies into electrics and non-electrics: also into conductors and nonconductors. Insulation. Circumstances affecting the conducting power of bodies. Difference in the electrical phenomena of bodies excited by different electrics. 12 Bodies similarly electrified repel each other : but when excited with electricity of different kinds, they attract each other. Circumstances which determine the kind of electricity, when any particular electric is excited. Electricity may be excited by friction, compression, expan- sion, fusion, evaporafion, crystallization, &c The forces of electrical attraction and repulsion are in- versely as the squares of the distances. Experiments on bodies charged with the two electricities- Phenomena of induction, or electricity excited by the in- fluence of a charged body at a distance. Franklin's theory of electricity. Du Faye's. Electrical machines: essential parts; theory of their action. Experiments with the electrical machine. Rapidity with which the electrical influence traverses con- ductors. Electrical, attraction and repulsion- Inflammation of various combustibles. Influence of points, &c. Electrometers. Gold leaf. Quadrant. Discharging, &c Electrophorus, theory of its action. Electrical spark. 13 a state of fusion. 2 Deposited from vapours. 3 From a solution. Definition of solution. Influence of temperature on the solvent power of fluids. Some substances equally soluble in hot as in cold wa- water, &c How crystals increase in size. Method of obtaining them perfect and large. Influence of a nucleus, threads, &c. on the crystallization of bodies. Modification of form in consequence of foreign substances in the solution. Circumstances which retard crystallization. Saturated so- lutions removed from the pressure of the atmosphere. Production of crystals influenced by electricity. Efflorescence. Deliquescence. Watery fusion. Rapid crystallization produces heat. Force with which water expands in freezing ATTRACTION, OR AFFINITY. It unites dissimilar particles and produce compounds poses- sed of new properties. Sometimes feeble, as when a salt unites with water.' Satu- ration. Proper chemical action is attended by remarkable phenomena. Change of properties by the union of dissimilar bodies ex- emplified by experiments. 1 Of chemical properties. 2 Of form. 3 Colour. 4 Den- sity. 5 Temperature- Chemical action influe»ced by cohesion. Most powerful X X- t 4 in liuids, and rarely takoi place where the acting bodies are both in a solid form. Influence of elasticity on affinity. How the union of mixed elastic fluids or gases is effected; 1 By pressure. 2 By heat. 3 By electricity. Vapours of dissimilar bodies have a strong tendency to combine. Solids unite with gases more readily when their cohesion is diminished. Union of elastic fluids with liquids and solids. When a body is capable of combining with a number of others, it attracts them unequally. Hence the ingredients of compounds may be disunited by the agency of superior af- finity. Experiments in illustration of this proposition. Some bodies appear to have no affinity for each other. Union of two bodies by the intervention of a third body. Methods of determining the degree of affinity which a body may possess towards a number of others. Tables of affinity. Geoffrey's. Kirwan's. Objections. Double decomposition. Diagrams for illustrating it. Neutrality which is observed after the decomposition of two salts. Chemical equivalents, or equivalent numbers explained. Uniformity of composition in compounds. Different, but definite, proportions in which bodies combine Law of multiples. __Combinations of gases