in his earlier works as an unknown friend, and in his later works telling us his name, and doing that justice to his character which before his death Mr. Gough had forbidden to be done. His occupation at this time, he says, was to read and write for Mr. Gough, and to participate with him in the pleasure of successful investigation. Mr. Gough was the first who kept a meteorological journal at Kendal, and led Dalton into that branch of inquiry. At this time Dalton's name may also be found often in the ‘Gentleman's and Lady's Diary,” it) which he answered mathematical and philosophical questions. But we must not so soon leave Mr. Gough. Dalton, in his preface, has paid him the highest tribute of respect; has acknowledged that he received a great deal from him, and considers the germ of all his discoveries to be contained in that portion of his works which was written whilst studying along with Mr. Gough. When we look at such a man, we may well ask the question—By whom is civilization advanced 1 Is it by him who is known to the world, or by him who is unknown The most difficult periods of a discovery, and the most dangerous, are the periods of birth and of growth. The first idea is dark and gloomy; it may be some mysterious-like feeling merely. The great man fosters it till it becomes clearer, till it takes a form; then it may be grappled with by a very ordinary man; but the last is looked on as the first, and the first is often unknown. Those who lived in that part of the country must have heard of Gough. Mr. Wordsworth has spoken of him in the “Excursion' in the following words, to which allusion we are indebted to Mr. Crompton, of Manchester:—

“Methinks I see him, how his eyeballs roll'd
Beneath his anple brow, in darkness pained,
But each instinct with spirit, and the frame
Of the whole countenance alive with thought,
Fancy and understanding; whilst the voice
Discoursed of natural or moral truth,
With eloquence and such authentic power,
That in his presence humbler knowledge stood
Abashed, and tender pity overawed.”

From 1790 to 1793 Dalton was engaged in making observations, and in the latter year published his “Meteorological Observations and Essays.” He then left Kendal and removed to Manchester. He is nowhere seen to more advantage than when, in the words of Prof. Sedgwick, he is bringing the turbulent elements themselves under his own intellectual domination.

These observations were continued with great care until the last day of his life, or rather the one preceding the morning of his death; on this last day he is said to have made a mistake in writing but afterwards corrected it. In this space of time he made upwards of two hundred thousand observations of various kinds relating to meteorology, and although the greater part are merely the noting down the state of the thermometer and barometer, this weary perpetuity of labor is more than most men can endure. No excitability made him pursue one subject when another ought to be attended to, no temptation led him out of his fore determined course. His observations on the weight of the atmosphere led him by degrees into chemical ground. He showed that every grain of water dissolved in air becomes an elastic vapor, capable of supporting 1-24th of an inch of mercury; that the rise of the barometer in summer indicated an increase in the amount of watery vapor in the air, and that the rise of the mercury did not depend on the specific gravity of the air only, otherwise summer and winter would show an equal barometer. He endeavored to connect the aurora borealis with magnetic phenomena, but found that this had been done before him by Dr. Halley. The same thing occurred with his explanation of the trade winds, which had been given long before by Geo. Hadley, F. R. S. Such mistakes occurred frequently, from the very little which he read; there are few branches of science which would allow of such proceedings at the present time, when observations are to be found so frequently in all departments, not certainly always of value but at least of some interest. In 1793 he went to Manchester, to be teacher of mathematics to the college there. In 1799, when the college removed to York, he separated from it, preferring to take private pupils, a practice which he kept up till late in life. It is a pity that he should have been so long employed in this manner, especially as he had no great talent for teaching, and his time would have been much better occupied in thinking and observing, but he is said to have preferred this when a more easily obtained competency was offered him, saying that teaching was an amusement, and that if richer, he would probably not spend any more time in study than he was then accustomed to do. About this time he wrote an English grammar, a book very little known, and its appearance seems anomalous, and difficult to account for, unless we suppose that circumstances of a pecuniary nature compelled him to study what he was certainly not naturally most inclined to. In this work the original thinker appears; a firm and independent character may be seen in it, although a mind like his is not best fitted for working with such changeable and volatile laws as those of grammatical inflection and construction. We shall merely take a short view of his writings and his career, attending chiefly to the character of mind displayed in them, and leaving more minute details to such as have documents relating to each particular event. His character of mind we have quoted from his writings as well as from his most intimate friends. In 1794, he became a member of the Literary and Philosophical Society of Manchester, when he read his first paper entitled “Facts relating to the Vision of Colors.” He had that peculiarity of vision which cannot distinguish between red, pink, purple, and blue. He says, “I was never convinced of the peculiarity of my vision till I observed the color of the flower of the Geranium zonale by candle light, in 1792. The flower was pink, but it appeared to me an exact sky-blue by day; in candle-light, however, it was astonishingly changed, not having any blue in it, but what I called red, a color which forms a striking contrast to blue.” He believed that this was to be attributed to the color of the fluids contained in the eye. It is true that there was found, on his death, a slight yellow color in the crystalline lens of the eye, but objects seen through it, when removed from the body, still preserved their natural color. His eyes being to himself an object of considerable speculation, his friends desired that they should be examined on his decease. They were extracted by his friend and medical attendant, Mr. Jos. Ransome, and have since been examined by Sir David Brewster, without any further result than the opinion that the cause was functional, not mechanical. Such a distortion of his color-sight could not fail to cause him some annoyance at times, and tales of his strange mistakes in dress are told of him. It is a pity that any one should have given the name of Daltonism to this strange vision, for we must remember that, after all, few eyes were so good as Dalton's and ought to

be connected with an expression of excellence rather than of desect. The list of his papers and their dates are given in one of the works before us; those from 1793 to 1804 gradually conduct us from meteorology to chemistry. Having come from Kendal, a meteorologist and mathematician, he advanced with all the cognate branches of investigation. He endeavors to determine the relation between the quantity of rain and dew, and the amount of water removed by rains and evaporation, the origin of springs, the power of fluids to conduct heat, the heat and cold produced by mechanical condensation and expansion of the air, the constitution of mixed gases, &c. He comes from the consideration of air and vapor viewed as an atmosphere to the same bodies in a more purely chemical point of view. He has given the elasticity of vapor at different temperatures, shown the method of determining the amount of vapor in the atmosphere, and the rate of evaporation at different temperatures. He makes important observations on the more mechanical properties of gases. Amongst these is diffusion of gases, at least as far as the mechanical part is concerned. The action of gases towards themselves, he explains, is not the same as towards gases of a different nature. The particles of each gas possess a certain repulsion towards particles of the same kind, but the particles of two different gases do not possess this repulsion. This is the reason, that if two bottles of gases of a different kind be connected even by a very small aperture, they mix completely in a very short time. Even if the upper gas be the light hydrogen, and the lower carbonic acid, both will be sound to be equally diffused through the upper and under bottle. He established also the law that all elastic fluids expand 1-480 every degree of heat from freezing point to 2129. It will still be impossible to give in this place all his researches, and we must now attend to those parts which are more purely chemical, as his name has risen chiefly by them, and he is best known in co, nection with them. It must, however, be remembered that the name of Dalton can stand high without the support of the atomic theory; the investigations which have been alluded to are a sufficient proof of this, and the improvements in meteorological observations, the great amount of data left by him, and the impulse given by him to the study, are works sufficient to point him out

as one of the few, who, in submitting to the take a view of the chemistry of the period of the discovery, at least as far as it regards quantity, a word scarcely used in chemistry at the time, and an idea not defined but by the atomic theory. Wenzel observed the fact of the mutual saturation of salts; when two salts mutually decompose each other, a certain quantity, ez. gr. four of soda saturates an acid, whilst fourteen of lead is required, and five of sulphuric acid are required when six or seven of nitric are necessary. Richter proceeded to analyze the different salts, and find the relative power of saturation of acids and bases, working on the fact known to Wenzel, the definite nature of the union which takes place between an acid and an alkali. He endeavored to establish accuracy in chemical calculations, but his view of the subject was too limited, his capacities of saturation were vague powers or forces, and wanted this unvarying unit which we shall see was introduced by Dalton, and gives the laws the form of a natural necessity. Bergman had some very good notions on the relations of oxides and metals; he weighed the precipitated oxide, and calculated its relation to the metal used, the mode certainly of arriving at an atomic weight, but in him also the possible took place of the necessary and unchangeable. Of all men who attended to this subject before Dalton, who saw most clearly how the matter stood, was Higgins, of Dublin. It is remarkable that in some places he has reasoned according to the true principles of combination, but not himself seeing clearly the foundation of his reasoning, he failed in coming to an universal expression for the facts. Or if he did see his way he failed in seeing its value, its use in investigation, its value in analysis, its many applications in theory and in practice, and its grandeur and beauty as a law of nature. He showed that a body uniting with oxygen took up first one particle, then another, and so on; that every particle united with a certain force, whilst the first particle would have a greater force than the secondd and the second than the third, calculating

labor imposed upon humanity have had the | calculated the combining power of bodies, pleasure of finding it worth more than the by numbers expressing force of attraction, food and the raiment or any other necessary a principle which could not have led to the or pleasure which it procured for self alone. first laws of the atomic theory with any

In considering the works of Dalton, the certainty, but which would have been found atomic theory must receive the chief atten- entirely at fault when compound atoms tion; and to know the change which chem- came to be spoken of If, however, his istry has undergone under it, we must first principles be insufficient, such cannot be

the force of combination by numbers. He

said of his words, which do express the atomic theory, and even the doctrine of compound proportions which may be gathered from them. Dalton's friends confess the former, the knowledge of the atomic theory, but claim for him that of multiple and compound proportions, lest he should lose all the honor: but the truth is, that where the one is well known the other must follow with ease. Higgins says, “Let S be a particle of sulphur, D a particle of dephlogisticated air (or oxygen) attracted by a force of 6; and let the compound be volatile sulphuric acid. Let us suppose a second particle of dephlogisticated air to unite to S, so as to form perfect vitriolic acid; to receive the latter, S must relax its tendency for the former one half.” In another part, again, he calls this a molecule of sulphuric acid, alluding to its union with bases. In another place (pages 36– 37 of the edition, London, 1791) he says, “100 grains of sulphur require 100 or 102 of the real gravitating matter of dephlogisticated air (oxygen) to form volatile vitriolic acid, and as volatile vitriolic acid is very little short of double the specific gravity of dephlogisticated air, we may conclude that the ultimate particles of sulphur and dephlogisticated air contain equal quantities of solid matter; for dephlogisticated air suffers no considerable contraction by uniting to sulphur, in the proportion merely necessary for the formation of a volatile vitriolic acid. Hence we may conclude that a single ultimate particle of sulphur is intimately united to a single ultimate particle of dephlogisticated air, and that in perfect vitriolic acid every single particle of sulphur is united to two of dephlogisticated air.” Considering that it was impossible at that time to see the true atomic weight of oxygen, we consider that Higgins had a good right to say that sulphurous acid contained one atom of each; and that if such be the case, the atomic weights of sulphur and oxygen are equal. This is reasoning in the true spirit of the theory. Had he ineasured more accurately, the addition in weight necessary to form sulphuric acid, he would have seen that it did not contain

a double quantity; but the truth is, that this could not be done directly, no means of obtaining it without water being known; and if we suppose he weighed it with an atom of water in it, he is certainly not far from the truth. But accuracy has nothing to do with the question: Dalton himself was never accurate, except in his general laws. We must give another quotation from Higgins (page 37). “As two cubic inches of light inflammable air require but one of dephlogisticated air to condense them, we must suppose that they contain equal numbers of divisions, and that the difference of their specific gravity depends chiefly on the size of their ultimate particles; or we must suppose that the ultimate particles of light inflammable air require two, or three, or more, of dephlogisticated air to saturate them. If the latter were the case, we might produce water in an intermediate state, as well as the vitriolic or nitric acid, which appears to be impossible; for in whatever proportion we mix our airs, or under whatsoever circumstances we combine them, the result is invariably the same. This likewise may be observed with respect to the decomposition of water. Hence we may justly conclude that water is composed of molecules, formed by the union of a single particle of dephlogisticated air to an ultimate particle of light inflammable air; and that they are incapable of uniting to a third particle, of either of their constituent principles.” The above is from the second edition. We have not the first edition before us; and certainly all of us will be willing to repeat with Higgins, quoting Horace on his titlepage, “Est quodam prodire tenus si non datur ultra.” But how we go ultra in this case, it is very hard to see; could it be said in plainer or truer language? So far as we know that it has never yet been done. It is almost painful, then, to be still inclined to repeat what we said above, that he was not gifted with a clear sight of the length and breadth and depth of his opinions. Had he continued reasoning in this mode he would have done all that Dalton has done, but he lost himself asterwards in the calculation of forces. His mind had the reasoning faculty predominating over the observing: it required a mind whose very reasonings were observations, whose every thought was a constant combining of physical properties, to carry this principle of combination into the whole extension of the science.

Whilst men were engaged in weighing simple bodies and compound ones, and obtaining their atomic weights, half consciously heaping proof upon proof, by mineral analysis, of the fixed laws of combination, proving daily that compounds contained always the same proportion of simple bodies, and actually expressing by clear words what occurred in the combination, we almost feel inclined to ask, was it necessary for Dalton to tell them what they meant It was necessary. We may mention, that Higgins published another edition of his work (Dublin, 1814), in which the phrases are adapted more to the language of the time. He wrote also many attacks on Dalton, who had never known of his existence at the time he published his theory, and whose only reply was, “Who can answer such abusive language *

We shall now give Dalton's announcement of his theory. At page 212 of the edition before us of the ‘New System,' he says, “In all chemical investigations it has justly been considered an important object to ascertain the relative weights of the simples which constitute a compound. But, unfortunately, the inquiry has terminated here, whereas from the relative weights in the mass, the relative weights of the ultimate particles or atoms of the bodies might have been inferred, from which their number and weight in various other compounds would appear, in order to assist and to guide future investigations, and to connect their results. Now it is one great object of this work to show the importance and advantage of ascertaining the relative weights of the ultimate particles both of simple and compound bodies, the number of simple elementary bodies which constitute one compound particle, and the number of less compound particles which enter into the formation of one more compound particle.”

Here is expressed with the greatest ease all that was wanted. The succession of his investigations had prepared him for this of course; but they had only made clearer and given a universal character to the opinions, or rather his perceptions of matter, which he shows to have been familiar to him from the earliest period of his career. Dr. Thompson says that Dalton first informed him that the observation of ole

ant gas and carburetted hydrogen first

led him to look into the inner constitution of chemical compounds. He found that if

we reckon the carbon in each to be the same, then carburetted hydrogen gas contains exactly twice as much hydrogen as olefiant gas. This seemed to point out clearly that if there be one proportion of hydrogen in the one, and two in the other, the same must hold good in all the smallest particles also; and proceeding to the ultimate particle, it must contain one atom of carbon and one of hydrogen. That this suggested to him the theory can scarcely be considered quite correct. It may have first given him clear notions of its value, but his prior investigations all show that his mind was saturated, we may say, with the atomic theory, from his first appearance before the public. That the examination of these gases was one of the important processes through which the truth became perfected, we can well believe; and probably the order of investigation has been nowhere better given than by Dr. Wilson, of Edinburgh, in the ‘British Quarterly Review.” His own investigations, his own experiments, were brought as proofs of his own conclusions; and when these gases were examined, the whole result seems to have fitted so well with his previous ideas as scarcely to have surprised him. Accordingly we find that he left Dr. Thomson, of Glasgow, to deal the subject to the public for several years, and when at last he published it, he brought it forward with little pomp, and as a truth beyond contradiction. When we give so much to those who worked upon the subject before Dalton, we do not mean to take any merit from him, and far out as they did work it they in nowise assisted him. This is not said from a knowledge of the facts that Higgins was unknown to him till 1810, and Wenzel and Richter till still later, and certainly not until some years after his discovery; but it is said from a knowledge of the nature of his own reasonings and the previous character of his mind displayed in his writings. The one idea which he had of atoms was so clear that all the others naturally flowed from it. Those who talked of the Wenzel and Richter salts, who spoke of the fixed forms of salts and minerals, and some gases, were now entirely silenced: the minerals, if constant, could not be otherwise; the salts, if not found constant, were considered to be badly analyzed; and this theory, if theory it be called, took immediate command of the finest balances, and endless theories

were found rapidly to disappear, hiding

themselves in the darkness which produced them. If any theory can be found simple, it is his; if any universal, it is his; if any can be found which may be said to be unchangeable through ages, it is his. It has no fear of future; no alteration in the science can affect it, no discovery of elements in our present elements can in the least alter it. But if it be desired that, we should believe that these combinations are formed by bodies with qualities such as he describes, hard and unchangeable, and that they approached each other in the manner in which he paints them,-an opinion to which he unfortunately attached much importance, —then must we, in company with the greater portion of thinking men which we have met, consider such an hypothesis as scarcely conceivable by the greatest stretch of his fancy, although some actually consider it to be the simple common-sense explanation. But not to follow that subject: the idea of Dalton, as it was the germ of all that was known both before and after him, explained also why the weights of atoms should be in reciprocal proportions. In fact, to the truth then known it distinctly said, it is so, it cannot be otherwise; to the falsehood it said simply, such is not the case; and no one has been required either to confirm the one, or able to render infirm the other. It may appear remarkable to some that we should talk of the atomic theory, and still talk of its undisputed stability. The word theory is used in its sense of a thing well seen, hot in the sense in which it is sometimes used, as a thing dimly seen; and the practice of the age allows both meanings to the word. The combining proportions of bodies are known, and are not vague, nor can any thing change our view of them but a change in Nature's self. The idea of numberless hard bodies called atoms, created in the beginning, and imperishable but by a fiat of the Creator, saying, “Let there be nothing where the earth now is,” is an hypothesis against which proofs sufficient could be brought, much beautiful matter might be written; but science is not yet in a position to give an explanation which shall express the universal feelings and opinions of men upon the subject. As chemists now use the term, the atomic theory is no hypothesis; it is the doctrine of combining proportions,—a law so universal, so beautiful, so unerring, so utterly without any repeal in the highest or lowest courts of explored nature, such a sure guide to those works of nature which it superin

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