Prehistory of the Philosophy of Chemistry

In his anti-atomism, philosopher-chemist Ostwald aimed, first, to distinguish between what is given in experience and what is postulated by the mind: nothing compels us to affirm that mercury ii oxide “contains” mercury and oxygen. Second, he aimed to show that energy is the most general concept of the physical sciences.In his Faraday lecture of 1904 he still argued vehemently against the atomic theory and, acknowledging his debt to Franz Wald,24 stressed that the deduction of the laws governing the nature of substances must start from the conception of “phase,” a concept far more general than that of substance. Ostwald was one of the first physical chemists to give reasonably precise empirical (macroscopic, thermodynamic) definitions of chemical substances. In his terminology, if the properties of two coexisting phases remain invariant during a phase change, the system is called hylotropic. If it is hylotropic over a range of temperatures as the pressure varies, it is a pure chemical substance. If it is not, it is a mixture. If it is hylotropic over all pressures and temperatures except the most extreme ones, it is a simple substance.

In 1907, while addressing metamerism, polymerism, and the role of valence in structure theory,25 he acknowledges that when compared with “structure theory,” his account in terms of differences in energy content “predicts, however, nothing whatever about the chemical reactions which are to be expected.” He further acknowledges “the spatial arrangement of elements” to be “a very important aid.” When the results of the experiments of Thomson on ions in the gas phase and Perrin on Brownian motion became available Ostwald finally surrendered in November 1908:26

The French chemists Felix de Lalande and Georges Chaperon, in 1882, realized the first alkaline battery. The rechargeable cell comprised a zinc and a copper oxide electrode in potassium hydroxide solution and delivered a voltage of 0.85 V. Up to that time, acidic electrolytes had been used for batteries only.

In 1944, Samuel Ruben (USA) licensed his aqueous zinc–mercury ii oxide primary button cell to a company owned by Philip Rogers Mallory, which came to be known later as Duracell company. The principle of the alkaline cell, namely substituting manganese dioxide for mercury ii oxide in the Ruben cell, was discovered in the late 1940s. The Canadian inventor Lew Urry patented the first modern primary alkaline battery in 1959. The alkaline manganese battery, a variant on the Leclanché cell, utilizes electrodes of zinc and manganese dioxide, but the electrolyte is potassium hydroxide. It took a further decade of development before the mature product was introduced by Ever ready and Duracell between 1968 and 1970.

In 1992, the rechargeable alkaline manganese battery was invented by Karl Kordesch (Austria), who worked in Canada for several years. Ordinary depleted alkaline batteries have commonly been recharged in households, although not endorsed by manufacturers because of the generation of hydrogen gas. As well with the reusable alkaline batteries, with each recharge less capacity could be reclaimed, and the deeper the discharge, the fewer cycles the battery can endure. Reusable alkaline batteries quickly replaced disposable household batteries in low-power applications, portable entertainment devices, and flashlights. The battery's limited cycle life is compensated by low self-discharge. However, the delivered current is insufficient to power most mobile phones and video cameras.

The histologist’s work is far from exempt from health hazards. Besides some common cuts and bruises when handling microtome blades and knives, many chemicals pose significant threats to staff and environment. To begin with, the user must be aware that, in contact with human tissue, fixatives will do exactly what they are intended to do: fixate. In addition, most individual components of fixatives are extremely hazardous and, moreover, volatile. It is the example of acetic acid, chloroform and, of course, formaldehyde, which has the particular nuisance of being carcinogenic. Some fixatives are also prepared with highly toxic metals, like mercury ii oxide, whose hazards do not require introduction, many of which are volatile. Even the most commonly used fixative for electron microscopy contains cacodylate (cacodylic acid), which is a synonym for dimethylarsinic acid, thus containing arsenic as the name implies, which may form volatile compounds. Osmium tetroxide, another excellent fixative, is probably the most dangerous reagent in the histologist’s laboratory and is volatile up to the point of not being blocked by plastic sealants and containers. Dyes are not barren of hazards either. Even if the pigment itself is innocuous, the working dye is prepared by adding organic solvents, acids, and metals. One must not surrender to oblivion the fact that histology requires handling of significant amounts of corrosive and flammable fluids.