Thomas Graham

 Thomas Graham spent his life in reading the book of Nature, and giving to mankind a knowledge of the truths

which he found there. His greatness is to be measured not merely by the amount and importance of the know

ledge which he thus gave, but even more by the singlenessand strength of purpose with which he devoted his whole

life to labours of experimental philosophy.

 

Some men have made important discoveries by occasionfllyapplying to experimental investigation, powers of mind

which they exerted usually in the pursuit of their own worldly advancement.

 

But from an early age Graham's one great object of life was the discovery of new truths, and he appreciated so fully the value of such work that he resolved to make any personal sacrifices which might be needed for its sake. And nobly he kept his resolution; for at an early stage of his career he endured, for the sake of pursuing chemistry, privations and sufferings so severe, that they are believed to have permanently injured his constitution; and at its very end, long after he had attained a world-wide reputation, when his delicate frame sorely needed the repose which was at his command, he continued to labour even more effectively than before, and to enrich science with

new discoveries.

  

It might be difficult to find in history a character so perfect in its noble simplicity and elevation.

 

Graham was born at Glasgow, on the 2 I st December, i8o5, the eldest of a family of seven, of whom only one survives.

 

He went to the English preparatory school at Glasgow, in i8ir, and was there under the care of Dr. Angus. In

the year 1814 he was removed to the High School, where language) were directed by Dr. Dymock, and subsequently

for one year by the Rector, Dr. Chrystal, under whom he studied Greek. It is said that during these five years hc

was not once absent at school-time. In 1819 he commenced attendance in the University classes in Glasgow.

 

 

Thomas Thomson then occupied the Chair of Chemistry, and young Graham benefited by his instruction, as also by

that of Dr. Meikleham, the Professofof Natural Philosophy.

 By this time he had already acquired a strong taste for experimental science, and formed a wish to devote him

self to chemistry. His father, an able and successful manufacturer, had formed different views for his future career, and wished him to become a minister of the Scotch Church. It is hardly to be wondered at that the fathcr should not have seen in the prosecution of science much scope for an honourable or advantageous career; but young Graham had already seen something of the means afforded by experimental science of getting knowledge fi-om the fountain head—from Nature herself. He felt the need of more such knowledge to mankind, and his scheme

of life was formed accordingly.

 

 

After taking the degree of M.A. at Glasgow, he continued his studies for two years at Edinburgh, and there

studied under Dr. Hope, and enjoyed the friendship of Prof. Leslie. On his return to Glasgow, he taught mathe

matics for some time at the. suggestion and under the patronage of Dr. Meikleham, and subsequently opened a

laboratory in Portland Street, Glasgow, where he taught chemistry. It is probable that some of the severest trials

of his life occurred at about this period.

 

While absent from Glasgow he was in the habit of writing regularly and at great length to his mother, and

from the tenor of these letters it is easy to see what that mother must have been to him. A writer on the social

position of women has described the feelings of boys towards their mothers as scarcely amounting to respect

I

Young Graham's mother seems to have been his guardian angel, sympathising with his hopes and his sorrows;

and certainly his feelings towards her would have been very inadequately described by that frigid word. While

studying at Edinburgh he earned, for the first time in his life, some money by literary work, and the whole sum (61.) was expended in presents to his mother and sisters.

 

 

In 1829 he was appointed lecturer on Chemistry at the Mechanics' Institution, Glasgow, in place of Dr. Clark;

hut the decisive step of his life was in the subsequent year. It was in 1830 that he was appointed Professor of

Chemistry at the Andersonian University, Glasgow; andit is said that his mother, who was on her deathbed, lived

to hear the glad tidings of his appointment. He was now more favourably circumstanced for experimental labours,

and we find that the seven years spent at the AndersonianUniversity were years of great activity, In 1837 he was appointed Professor of Chemistry in the London University, now called University College, London, and he occupied that chair with great distinction till the year 1855, when he succeeded Sir John Herschel as Master of the Mint, which appointment may be considered an acknowledgment on the part of the Government of his scientific services and of his high character.

 

His numerous discoveries have been much quoted. Some of their theoretical bearings claim a brief notice

here.

 

His investigation of the phosphates is remarkable in many ways. It was known that solutions of phosphoric

acid in water vary in their properties; and chemists were satisfied with giving a name to the changes without investigating their nature. These solutious contained phosphoric acid and water, and were assumed to

have like composition. They were accordingly called isorneric. Graham observed that they differ from one another in the proportion of water combined with the acid, and constitute in rcality different compounds.

He knew that water combines with acids as other bases do, and he showed that the various corn-

pounds of phosphoric acid and water constitute distinct snlts, each of which admits of its hydrogen being replaced by

other metals without disturbance of what we should now call the type. Thus, to use our present notation, the three hydrates PO4H,, P,O,H4, PO,H, correspond to the following proportions of acid and water .

 

 

Graham observed that the hydrate P04H3 is constituted like a salt, inasmuch as its hydrogen can be replaced atom

for atom by other metals, like sodium, potassium, &c., forming such compounds as PO4NaH,, PO4Na,H, &c.

 

 

In order to appreciate duly the powers of mind of the author of this admirable research, we ought to compare

his methods of reasoning with those generally prevalent among contemporary chemists, and on the other hand

with the methods of to-day.

 

One would fancy that Graham had been acquainted with the modern doctrines of types and of polybasic acids, so clearly does he describe the chemical changes in matter-of-fact language, and so consistently does he classify the compounds by their analogies. At that early period we find Graham considering hydrogen, in various salts, as a basylous metal; an idea which (in spite of its undeniable truth) some chemists of the present day have not fully realised.

 

Amongst minor chemical researches may be mentioned a series of experiments on the slow oxidation of phosphorus

by atmospheric air. He discovered that this process (atd the faint light which accompanies it) is arrested by the

presence in the air of a trace of oleliant gas, of the volume of the air being sufficient for the purpose. Still smaller proportions of some other vapours were found capable of producing this same effect; spirits of turpentine being particularly remarkable, as less than a quarter of a thousandth of its vapour with air was found sufficient to prevent the slow oxidation of phosphorus.

 

On another occasion Graham investigated phosphuretted hydrogen, and made some remarkable observations

concerning the conditions of the formation of the spontaneously inflammable gas. One of these deserves especial notice in connection with the action of olefiant gas, and in preventing the oxidation of phosphorus. He found that phosphuretted hydrogen is rendered sponta neously inflammable by the admixture of a. very small proportion of an oxide of nitrogen, probably nitrous acid.

 

One of the most obscure classes of combinations are those which water forms with various salts. These bodies

are characterised by the chief peculiarities which belong to definite chemical compounds; but chemists are as yet

unable to explain them.

 

Water so combined is called water of crystallisation, and is said to be physically, not chemically, combined. A very con-

venient way of getting rid of a difficulty, by passing it on to our neighbours.

Graham examined the proportion of such water of crys tallisation in a considerable number of salts, and he moreover examined the properties which it has when so combined. He found that some of the water in an important class of suiphates is held far more firmly than the remainder, and with force equal to that with which water is held in various chemical compounds. He showed that such firmly combined water can be replaced by salts in a definite chemical proportion, in fact, he got fairly hold of the subject by chemical methods, and laid the foundation for an explana-

tion of it.

 

He discovered and examined compounds of alcohol with salts, and derived from them valuable evidence of the analogy between alcohol and water.

 

On a later occasion he made a series of important experiments upon the transformation of alcohol into ether and water, by the action of hydric sulphate. Liebig had endeavoured to explain the formation of ether in this process, by representing it as due to the decomposition at a high temperature of a compound of ether previously formed at a lower temperature; such decomposition being due to the increased tension of the vapour of ether at the higher temperature.

 

Graham justly argued that if the decomposition were due to the tension of ether vapour,it would not take place, and ether would not be formed, if the tension were not allowed to exert itself. He heated the materials in a closed tube, and proved that ether was formed, although the tension of its vapour was counteracted by the pressure thus obtained.