Translator J. A. Schufle
I
New Mexico Highlands University Las Vegos, New Mexico
Torbern Bergman a n d Andreas
The Different Quantities of Phlogiston in Metals
No species r m a i n a unchanged; and she that renews things, nature, m e a t s one speeiesfrom another.
.. .Ovid
I. The Amount of Inflammable Element
Phlogiston is found to be disseminated like an element in all natural bodies, at least in the earth, with the difference that as a rule it preferably exists with notable abundance in those bodies which are usually called organic. I n fossils, the greater part of which are known to be more sparing [in phlogiston] but not so much less in strength that any of them can be shown to be entirely deprived, or if [phlogiston] is secretly concealed according to all other criteria, [phlogiston] is easily noticed from the colors with which all are clothed, and which no doubt indicate the phlogistic source. This most subtle element, which displays such transparency, that it alone escapes all of our senses, is confined by no apparatus of instruments, and therefore bas eluded all chemical investigation, unless it should adhere with strong attraction to some other material, but unequally and selectively, so that it could be transferred easily from one compound to another. Thus by careful comparison of properties before and after union with phlogiston, one can learn something about the substanceand the nature of that element. It displays really amazing activity, changing things in an extraordinary way because of differences in its quantity. We see concentrated vitriolic acid, destitute of odor and color, with its help, expanding into an acid air, exceed-
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ingly volatile and elastic, which has similar external properties, only heavier, to [ordinary 1 air, but provided with a very penetrating and suffocating odor; that in turn to be condensed into solid sulfur, free from corrosiveness, taste, and nearly free from odor. Such metamorphoses, which are the result of new combinations, or different proportions, are among the works of nature to be investigated, by means of properly arranged experiments, in order to explore the multifarious [forms],identified by clever invention. Preceding Beccher, the great Stahl as it were created the doctrine of Phlogiston, which succeeding chemish have refined in distinguished works of science and natural philosophy, but up to this point few have reflected upon the measurement of the quantity of this element in different materials. We marvel at the industry of astronomers who, laboring strenuously in determining the magnitudes and distances of the heavenly bodies, will have been able to find out totally exact measurements, but continually employ values only approximately and for the time being relatively correct with the greatest profit in their calculations. Why can me not work to determine, at least in relative amounts, that part of inflammable bodies vhich corresponds on earth to the planets in the opinion of the alchemists? This might enlighten Metallurgy in the greatest possible way. Stahl has already tried to determine quantitatively the common ingredient, sulfur; and after him no one else; but renowned in all this difficult exercise of t,he mind, as in all things, is the
illustrious Divonian Chemist, Mr. de Morveau, who is happily venturing to elucidate by different experiments the nature and properties of phlogiston. [Original dissertation reads: "Mr. de Morvcau, who is entering into this [field]accompanied by troops of Physicists and Mathematicians, each of whom, after him, also represents fruitfully in numbers the attractive strength of mercury in other metals."] I n this Dissertation we endeavor to determine in a new way the reciprocal proportion of the inflammable element in metals. What is lacking can and ought to be supplied by many more investigations. II. Are Metals Precipitated From Acids by Action of Other Metals Through Double Attraction?
[In the original edition this title is phrased as a declarative sentence and not as a question.] These displacements of metals have always been considered as t,he effect of simple elective attraction, which chemists have believed holds the completed metals in solution. Now, however, it is disclosed to sufficient degree and more, that no metal can be dissolved by acids unless sufficient phlogiston has previously bccn removed. Calcinated [metals] therefore adhere morc or less to the solution, and another metal being added, are unable to precipitate as the completcd mctal unless the lost phlogiston is recovered, and this [phlogiston] is drawn from no other material than from the precipitant [metal], which has still to be complctcly deprived of it before it [the metal] can enter into solution.' Calces, as shown by experiment, do not ordinarily displace themselves, at, least not in the same way as metals. Is it not evident therefore that t,he amount of reducing phlogiston in any metal can be determined by comparing the weight of precipitated [metal] and that of [the metal] causing precipitation? The following experiments give the answer, but before [we consider] these, let us examine according to classes those cases which can occur in this reaction. Let A bc the metal causing precipitation [i.e., the metal dissolving], m the weight of acid necessary for dissolving 100A, x the amount of reducing phlogiston in 100A, B [the metal] which is about to be precipitated [i.e., the metal coming out of solution], nm the weight of the aforementioned liquid [acid] used to dissolve 100R, and y the amount of reducing phlogiston in 100B. n can be either equal to one, greater than one, or less than one. (I) Let n = 1, so that m = nm. I n this case, if x = y no difficulty occurs, because the liquid is able to dissolve equal weights of both [metals], and B can recover from A all that is necessary of the inflammable matter [phlogiston], whatever amount of reduction is necessary. If x > y nothing additionally seems to happen by which a less than perfect precipitation occurs. However, if x < y, so that B can be only partly displaced, unlcss that [metal] causing precipitation is visibly given up to solution, and just this new portion can be dissolved, then another met,hod must be sought. (11) Now let n > 1 , and m will be < nm. Here the same cases are restored with respect to phlogiston as in operation (I), hut all difficulties arc less. (111) Let n < 1 , and m will be > nm. Now B cannot be completely precipitated, unless nx = y or nx > y,
so that such an amount of precipitant as n lOOA is dissolved. First we made preliminary experiments which showed many variations. However since fifteen different metals are known, each of which considered separately might require more than one hundred attempted precipitations, which could not be explained in a fev pages, therefore we have chosen at most two [metals] as sufficient to be examined more closely, namely silver, which is precipitated in the majority of cases, and zinc which is never precipitated. Ill. Precipitations of Silver Brought about by Olher Metals
Silver can be precipitated from nitrate solution by almost all metals with the exception of gold and platinum. That we may understand these reactions better let us examine each one separately. (a) 100 equivalent partsZof silver carefully measured were so dissolved in nitric acid that the solution could hardly receive a greater amount of this metal. Indeed witb all metallic salts this ability is enhanced by the presence of the sugar of red Heliotrope, but an excess of this cannot be taken up without decomposition of the salt. Therefore in our solutions, we try to make the excess to he as small as possible, and likewise t,he weight of precipitant [metal] is made no greater than is just necessary, which [weight] we propose in the end t o know accurately. In this way the precipitation proceeds more slowly to be sure, but it can be completed witb few cases excepted. I n all experiments we have employed one hundred, i.e., 100, carefully measured equivalent parts of t,he metal to be precipitated [silver] and tried to obtain the highest degree of saturation possible, unless it is otherwise recommended in express words. One hundred [parts] of silver being so dissolved and diluted twice with distilled water, successive portions of mercury werc added which added together made 490 parts. Some trees were produced which are called by the name of Diana, but provided with varied forms according t,o the different amounts of silver dissolved and the reciprocal proportions of mercury being put in. Using some method of exchange or other, the liquid metal [mercury] is put into solution richer than those [metals] being precipitated, and for the most part they come out more slowly when it is used, but finer, more brilliant, and more dense, and also sometimes crystalline and prismatic. The mercury put in at first s l o ~ l y becomes stiff, then the surface becomes irregular and finally branches grow up which are seen to increase and multiply gradually. The branches, collected, washed and dried, make up 455 parts, of which 455 100 = 355 [parts] are made up of mercury, while 490 355 = 135 [parts of mercury] adhere to the acid solution. The clear liquid, mercury being put in afterwards, emitted nothing in ten days nor was anyt,hing emitted when heat of digestion was employed. And so 135 [parts] of mercury by its phlogiston had reduced 100 dissolved and calcinated [parts] of silver to a complete metallic form, which, united with almost four times Two parapaphs omitted here in this digest. Bergman used the Latin word l i b m which we translate parts or qu?raimt par& and explain in our paper in Isis [in press (197111. 1
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[its weight] of mercury in an amalgam had formed growing crystals. (b) Lead uses 234 parts, necessary for the precipitation of 100 parts of dissolved silver. The piece of lead put in is soon blackened, but within a few moments is discovered to be surrounded by a silver shell and covered with shiny crystals. The last vestiges come down more slowly, unless heat of digestion is used here, as in most other cases. The collected precipitate never exceeds one hundred by more than 8 or 10 parts, which are derived from visible powder of calcinated lead (V,eP. IV. Precipitations of Metals Brought About by Other Metals, Preferably Zinc
( a ) One hundred [parts] of pure gold dissolved in aqua regia, with as little excess acid as possible, so that it precipitates perfectly, required 217 parts of zinc. (b) An equal amount of gold, precipitated by 301 parts of English tin, gives 66 [parts] of restored gold and 160 [parts] of a purplish black powder. The remaining liquid became purple, but refused decomposition by more tin in moderate heat. This was displaced by 158 parts of zinc, producing a purplish powder, which when washed and dried equaled 212 parts. (c) One hundred [parts] of common platinum, so dissolved in aqua regia that the liquid can dissolve no more metal cvcn if it is boiled, nevertheless devoured not less than 416 parts of zinc t o saturation. The bloody color was soon after the beginning made turbid by black molecules, which were produced with violent effervescence. All internal motion having stopped, a black powder settled out, which when collected, washed and dried amounted to 77 parts, but the clear liquid remaining was yellow and with a little evaporation produced yellow crystalline grains, especially if some vegetable alkali was added. The powder grows black on carbon, whcn a blow-pipe is used, the part exposed to the flame belching forth white fumes from the first moment and the ignited part returning to bright metal, not white however, but ashy like common platinum. It is not attracted by a magnet either before or after ignition. (d) Silver has been investigated with respect to zinc previously (111, m). (e) One hundred parts4 of mercury seem to require 44 of zinc to be precipitated completely from nitrate solution. Zinc causes difficulty with the reduction of soluble m e r c u ~ y . ~ V.
Conclusions
Of the experiments now collected together for comparison and consideration, many are noted to have special importance. Namely: (a) That metals m a y be subjected to different degrees of dephlogistication in different acids. Thus 100 parts6 of silver dissolved in nitric [acid] are reduced by 31 [parts] of copper, but united to vitriolic [acid] only 30 [parts of copper] areneeded (111, c, d).? (b) When we put solutions under examination, saturated as much as possible, we learn that the quantities of phlogiston given in exchange by the precipitant and precipitated [metals] are inversely proportional to the weights. Therefore the amount of phlogiston in 100 [parts] of silver is expressed by 100, and will be designated in the same way by 74 in 812
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one hundred [parts] of mercury, by 43 in lead, by 323 in copper, by 342 in iron, by 114 in tin, by 57 in bismuth, by 156 in nickel, by 109 in arsenic, by 270.in cobalt, by 182 in zinc, by 120 in antimony, and by 196 in magnesium [manganese] (111). (c) These numbers are improved by comparison with others from precipitations in which the amount of phlogiston in one hundred [parts] of zinc is expressed 182, the value we have just found. This being decided upon, the following [numbers] are brought forth by t,he same method: from one hundred [parts] of gold namely 394, from platinum 756, from mercury 80, from lead 47, from copper 290, from bismuth 64, and from antimony 217 ( I V ) . These numbers, although obtained from experiments, need nevertheless to be established and corrected by many more trials. Of these moreover none seem more dubious to us than that pertaining t,o platinum. Yet we persuade ourselves that 77 equivalent parts of precipitated [platinum] have absorbed the total quantity of phlogiston which 416 parts of zinc contain. Visible effervescence from beginning to end denies that. Meanxrhile we have been unablc to make any other more accurat,e estimation. This, as in many other cases, is because of the peculiar nature of platinum. Differences between the two scries, not very great in the majority of numbers, are to be minimized by repeated experiments. In cases of difference, however, we place the most confidence in the [value] which is found in 111, because solutions of silver are easily tested with a seed of chloride as to xhether or not they will have been completely precipitated; silver, once reduced, does not lose [its] completc nature in the liquid or [its other] remaining proper tie^.^ (h) After the preceding experiments are completed [the metal] richest in phlogiston will be platinum, then gold, iron, copper, cobalt, magnesium(manganese), zinc, nickel, antimony, tin, arsenic, silver, mercury, bismuth and lead, in that order, [the richer being] that ~rhich approaches nearer to the first metal. However, the relative numbers, designating the amounts in each case, are to be investigated at once by other methods. The investigation of cert,ain metals whose attractions arc now questionable may become most difficult work, but if experiments even of doubtful accuracy u'ill be attempted, and if they will be repeat,ed often enough, t,he average of many results will eventually be better. If thus mercury, and also lead, and thirdly copper, and so on in turn to those of the rest [of the metals] which deserve attention, are chosen to he examined, we will have then many scries of trials which, when properly evaluated, \rill disclose fewer variations in properties worthy of note, and also \rill detcrmine the relativn amounts with exactness. This being done, if ever one [metal] allows its absolute value to bc found by diligent experimentation, all the others are known quickly. a The next twelve paragraphs discuss similar experiments with copper, iron, tin, bismuth, nickel, arsenic, cobalt, zinc, antimony, and manganese. They are omitted in this digest. Here Bergman uses the Latin word parles and thus gives the correct interpret,ation of the word libra which he uses elsewhere with the same meaning. The next t,welve paragraphs discuss similar experiments on t h e metals copper, iron, tin, bismuth, nickel, arsenic, cobalt, antimony, and manganese. They are omitted in this digest. Here again Bennan uses t,he Latin word parks. Remainder of this paragraph omitted in this digest. Four suoceedillgperagraphs omitted here in this digest.
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