Phlogiston

“ To this head we refer all fossils containing phlogiston in such great abundance, that under proper management they are inflammable. The Genera are obviously very few, and accurately speaking there is only one Genus. But since phlogiston is so very subtle as not by itself to become the object of our senses, it will perhaps be adviseable to consider its more simple combinations as Genera: this has long been done so far as respects the metals, by universal consent.
64 SULPHUR.
§ 133. ”

“ According to Stahl, phlogiston is a real substance, capable of being transferred from one body to another; its presence or absence making a remarkable difference in the properties of bodies, whether it add to their weight or not. ”

“ But, he said, when it is absorbed into a metal or other substance it does not combine with that substance, but is constantly in motion in the interstices of the molecules. So that as a bird in a cage does not add to the weight of the cage so long as it is flying about, no more does phlogiston add to the weight of the metal in which it is similarly flying about. But when the calcination takes place the dead phlogiston, as it may be called, does actually combine with the metal, and thus the increase of weight is accounted for. ”

“ This earth, when heated with substances rich35 in phlogiston, such as coal, wood, flour, and similar bodies, recovered the phlogiston, which it had lost on burning, and, with the added phlogiston, its metallic character. Other substances, such as phosphorus and sulphur, gave solids or acid liquids, to which phlogiston was not so easy to add; but even they could be rephlogisticated. On this hypothesis, it was the earths, and such acid liquids as sulphuric or phosphoric acids, which were the elements; the metals and sulphur and phosphorus were their compounds with phlogiston. ”

“ Plants will not thrive unless both their leaves and roots be exposed to air in some degrees impure. This I have fully ascertained, but I am afraid that the doctrine is not capable of much practical application.
‘I know of no method of conveying phlogiston to the roots of plants but as combined with water, and this seems to be done in the best way by a mixture of putrid matter. Water will not imbibe much inflammable air. I find volatile alkali to contain much phlogiston. ”

“ Looking back, we cannot think of phlogiston as a substance, or as a thing, in the modern meanings of these terms as they are used in natural science. Nowadays we think, we are obliged to think, of the sum of the quantities of all the things in the universe as unchanging, and unchangeable by any agency whereof we have definite knowledge. The meaning we give to the word thing rests upon the acceptance of this hypothesis. But the terms substance, thing, properties were used very vaguely a couple of centuries ago ”

“ Water—no longer a simple substance—is formed by the union, weight for weight, of oxygen and hydrogen. Lavoisier’s reasoning was so sound112 and his experimental evidence so complete that his views gradually gained acceptance in France. The phlogiston myth was thus exploded. Inspired by Lavoisier, a small band of French chemists—Berthollet, Fourcroy, Guyton de Morveau—thereupon set to work to remodel the system of chemistry and to recast its nomenclature so as to eliminate all reference to phlogiston. ”

“ To obtain phosphorus, a good proportion of coal (regarded as a type of phlogiston) was added to urine, previously thickened by evaporation and preferably after putrefaction, and the mixture was heated to the highest attainable temperature. It was obvious that phlogiston entered into the composition of the distillation product. The question remained whether this product was generated de novo. In his research of 1743 to 1746, Andreas Sigismund Marggraf (1709-1782) provided the answer. ”

“ Combustion meant the liberation of phlogiston. Metals on calcination gave calces from which the metals could be recovered by adding phlogiston, and experiment showed that this could generally be effected by the action of coal or carbon, which was therefore regarded as practically pure phlogiston; the other constituent being regarded as an acid. At the hands of Stahl and his school, the phlogistic theory, by exhibiting a fundamental similarity between all processes of combustion and by its remarkable flexibility, came to be a general theory of chemical action. ”

“ The history of science can show many instances whereby the rule has been demolished by the exception. Little facts have killed big theories, even as a pebble has slain a giant. During the reign of phlogiston a few of such facts were not unknown—at least to some of the better informed of Stahl’s followers. ”

“ The identity of Phlogiston in all combustible bodies was founded upon observations and experiments of so decisive a nature, that after the existence of the principle itself was admitted, they could not fail to be satisfactory. When phosphorus is made to burn, it gives out a strong flame, much heat is evolved, and the phosphorus is dissipated in fumes, which, if properly collected, will quickly absorb 420 moisture from the atmosphere, and produce an acid liquid known by the name of phosphoric acid. ”

“ Since inflammable, air, by agitation in water, first comes to lose its inflammability, so as to be fit for respiration, and even to admit a candle to burn in it, and then comes to extinguish a candle; it seems probable that water imbibes a great part of this extraordinary charge of phlogiston. And that water can be impregnated with phlogiston, is evident from many of my experiments, especially those in which metals were calcined over it. ”

“ It is no easy matter to give a satisfactory answer to this question. But, without pretending to guess the cause of the phenomenon, let us rest contented with the certainty of the fact, the knowledge of which will undoubtedly procure us considerable advantages. Let us therefore examine the properties of Fire thus fixed, and become a principle of bodies. To this substance, in order to distinguish it from pure and unfixed Fire, the Chymists have assigned the peculiar title of the Phlogiston, which indeed is no other than a Greek word for the Inflammable Matter ”

“ He then goes on to say that the arguments in favour of this opinion, especially those which were drawn from the experiments of Lavoisier on mercury, were “so specious” that he owns he was much inclined to adopt it. But he was evidently loth to part company with a conception which had hitherto been the central idea of his chemical creed, the very key-stone of the structure which he was pleased to regard as his philosophy. As an abstract conception, as the principle of levity, as something which was the negation of mass and which gravity repelled, phlogiston was eminently unsatisfactory. ”

“ These two metallic substances scarce resemble each other in any thing, but the qualities common to all semi-metals.
Zinc melts the moment it grows red in the fire, and then also begins to turn to a calx, which, like any other metallic calx, may be reduced by means of the phlogiston: but if the fire be considerably increased, it sublimes, flames, and burns like an oily matter; which is a proof of the great quantity of phlogiston in its composition. At the same time abundance of flowers rise from it in the form of white flakes, flying about in the air like very light bodies ”

“ In general, the more of their phlogiston they have lost in the calcination, the more difficult is their vitrification. This causes also a difference in the colour of the Glass; which will be of so much a deeper yellow, and the nearer to a red, the less the Antimony was calcined.
It frequently happens, when we employ a calx of Antimony which is not sufficiently deprived of its phlogiston, that we find in the crucible a button of Regulus, which, be [Pg 331] ing heavier than the Glass, always lies at the bottom. ”

“ The phlogistic theory savoured of alchemy; it postulated an undefined, undefinable, intangible Principle; it said that all combustible substances are formed by the union of this Principle with another, which is sometimes of an earthy character, sometimes of a fatty nature, sometimes highly volatile in habit. Nevertheless, the theory of Stahl was a step away from purely alchemical conceptions towards the accurate description of a very important class of changes. The principle of phlogiston could be recognised by the senses as it was in the act of escaping from a substance ”

“ It seems, however, clearly to be inferred ... that there is no occasion to admit the alkaline principle into the 222 number of elements; the alkalinity, as I may say, some way or other, arising from phlogiston, or phlogisticated air, as acidity arises from dephlogisticated air.”
After these theoretical speculations, “in which,” he says, “I fear I have not communicated much light, though it is as much as I have been able to get,” Priestley proceeds to make some observations relating to phlogiston, “the existence of which is at present a great subject of discussion with philosophers ”

“ By saturating phlogiston, Professor Bergman means to express the proportionate quantities taken away from each metallic substance, when dissolved by means of acids, and of course reduced to a calciform state. The last column only expresses their attractions to this part of their phlogiston, not to that which still remains united to them in a calciform state. W.
56. ”

“ It may be noted here that, while Cavendish adhered to the phlogistic doctrine, he did not hold it with anything like the tenacity that characterized Priestley; thus, in his 1784 paper on “Experiments on Air,” he remarks that not only the experiments he is describing, but also “most other phenomena of nature seem explicable as well, or nearly as well,” upon the Lavoisierian view as upon the commonly believed principle of phlogiston, and he goes on to give an explanation in terms of the antiphlogistic hypothesis. ”

“ It is highly improbable that what remains after an [Pg 140] animal body has been thoroughly dissolved by putrefaction, should yield so great a quantity of inflammable air, as the dried animal substance would have done. Of this I have not made an actual trial, though I have often thought of doing it, and still intend to do it; but I think there can be no doubt of the result.
Again, iron, by its fermentation with brimstone and water, is evidently reduced to a calx, so that phlogiston must have escaped from it. ”

“ One consolation remains, that in your experiments you cannot fail of discovering something perhaps of as great or greater importance for us to know.”
Nevertheless, even in the Club itself there was at least one man who came under the influence of Priestley, but who eventually emancipated himself, and this was Withering, who, we are informed, read to them “a humorous piece in verse entitled ‘The Life and Death of Phlogiston,’ which was long remembered for its clever treatment and pointed wit.” ”

“ Now Nature has made no organ for clearing away phlegm, this being cold and moist, and, as it were, half-digested nutriment; such a substance, therefore, does not need to be evacuated, but remains in the body and undergoes alteration there. And perhaps one cannot properly give the name of phlegm to the surplus-substance which runs down from the brain, but one should call it mucus [blenna] or coryza—as, in fact, it is actually termed; in any case it will be pointed out, in the treatise On the Use of Parts, how Nature has provided for the evacuation of this substance. ”

“ Phlogoenas contains a score of members ranging from the Philippines and Timor to the Society Islands. P. luzonica of Luzon has purplish upper parts, a greyish-blue head, and yellowish-white lower parts, with a patch of stiff red decomposed feathers over the crop; the inner webs of the remiges are more or less rufous, a characteristic found also in Chalcopelia, Columbigallina, Scardafella, and Leptoptila, from very different parts of the world. ”

“ It is contrary to evolutionary theory that a specialized group would evolve into a generalized form and then evolve new kinds of specializations to meet the needs imposed by the same environmental conditions affecting the earlier specialized group. A more reasonable hypothesis is that the evolution of opposable digits took place in a phyletic line that had as its ancestral stock a frog with generalized hands and feet. If this assumption is correct, Phyllomedusa and Agalychnis represent different phyletic lines ”

“ The skeleton of Plagonium exhibits therefore the same remarkable form which is found in the isolated spicula of numerous Beloidea (e.g., Lampoxanthium punctatum, Sphærozoum punctatum) , and bears the same relation to Hexaplagia that Plagonidium does to Tetraplagia.
1. Plagonium sphærozoum, n. sp. (Pl. 91, fig. 6) .
Spines straight and stout, three-sided prismatic, about twice as long as the common middle rod, irregularly branched or nearly verticillate, with short thorny branches. Similar to the single spicula of some species of Sphærozoum and Lampoxanthium. ”

“ It is a fact familiar to Conchologists, that the genus Pholas, possesses the property of phosphorescence. It has been asserted, that this may be restored, even when the animal is in a dried state, by the application of water ”

“ Bütschli’s theory of Protozoan phylogeny implies that a flagellum is an organ of most primitive nature, possessed perhaps by the earliest forms of life; and it must be remembered that flagella are borne by many Bacteria. On the other hand, one would imagine, from general considerations, that living beings possessing a flagellum would have been preceded in evolution by others that did not bear so definite an organ. ”