Further Daltonian DoubtsAuthor(s): Robert SiegfriedSource: Isis, Vol. 54, No. 4 (Dec., 1963), pp. 480-481Published by: The University of Chicago Press on behalf of The History of Science SocietyStable URL: http://www.jstor.org/stable/228153 .

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NOTES & CORRESPONDENCE

FURTHER DALTONIAN DOUBTS

By Robert Siegfried *

In his recent paper, "Some Daltonian Doubts," 1 Henry Guerlac has reopened the question of the possible influences on the origins of Dalton's atomic theory. In particular he argues effectively to show that Richter's equivalent tables could have been known to Dalton early enough to have been significant. May I add new fuel to the flames Guerlac has fanned from the embers of this unsettled problem by suggesting that a part of Dalton's inspiration might have come from a source previously unconsidered.

In a paper2 read to the Royal Society on November 18, 1802, James Smithson reported that, based on his experiments, vitriol of zinc "in an arid state, consists of exactly equal parts of calx of zinc and vitriolic acid." 3

This result seemed to illustrate the simplicity found in " all those parts of nature which are sufficiently known to discover it.... It appears improbable that the proximate constituent parts of bodies should be united ... in the

very remote relations to each other in which analyses generally indicate them." He was led to the opinion " that, on the contrary, they are uni- versally ... fractions of the compound of very low denomination. Possibly in few cases exceeding five."

Among the examples of this simplicity based on his own analyses were the following.

Mendip Hill calamine carbonic acid 1/3 calx of zinc 2/3

Bleyberg calamine carbonate of zinc 2/5 hydrate of zinc 3/5

Bleyberg calamine (minus the carbonate) calx of zinc 3/4 water 1/4

It should be noted that these figures represent analyses by weight. There is not anywhere in the paper anything suggestive of equivalent weights. None the less, Smithson clearly recognized the possible significance of these simple fractions when he wrote the following.

* University of Illinois. was also printed in Nicholson's Journal, 1803, Isis, 1961, 52: 544-554. 6: 74-85.

2 A Chemical Analysis of Some Cala- 3 Loc. cit., p. 21. Smithson's emphasis. mines," Phil. Trans., 1803, 12-28. This paper 4Loc. cit., p. 22.

480 ISIS, 1963, VOL. 54, No. 178.

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FURTHER DALTONIAN DOUBTS FURTHER DALTONIAN DOUBTS

If the theory here advanced has any foundation in truth, the discovery will introduce a degree of rigorous accuracy and certainty into chemistry, of which this science was thought to be ever incapable, by enabling the chemist, like the geometrician, to rectify by calculation the unavoidable errors of his manual operations, and by authorising him to discriminate from the essential elements of a compound, those products of its analysis whose quantity cannot be reduced to any admissible proportion.

A certain knowledge of the exact proportions of the constituent principles of bodies, may likewise open to our view harmonious analogies between the constitutions of related objects, general laws, etc. which at present totally escape us. In short, if it is founded in truth, its enabling the application of mathematics to chemistry, cannot but be productive of material results.5

The foregoing statement might almost be taken for a prophetic descrip- tion of the virtues of the laws of definite and multiple proportion.

Whether this idea of numerical simplicity exhibited to Smithson from straight weight analyses suggested to Dalton a similar pattern using equiva- lent weights is a question I willingly leave to those better prepared and more inclined than I to pursue. Guerlac is properly cautious when he states that "if the Fischer-Richter Table was important to Dalton as early as 1803-4, it was not for the data it contained, but for the concepts of equivalent weights and the method of obtaining them." 6 Similar caution requires me to say only that if Smithson's paper had any significance in Dalton's genesis of the atomic theory, it was through Smithson's emphasis on the small numerical fractions expressing chemical composition. This in combination with the idea of equivalents based on the Fischer-Richter tables could have led Dalton to his chemical atomic theory.

If the theory here advanced has any foundation in truth, the discovery will introduce a degree of rigorous accuracy and certainty into chemistry, of which this science was thought to be ever incapable, by enabling the chemist, like the geometrician, to rectify by calculation the unavoidable errors of his manual operations, and by authorising him to discriminate from the essential elements of a compound, those products of its analysis whose quantity cannot be reduced to any admissible proportion.

A certain knowledge of the exact proportions of the constituent principles of bodies, may likewise open to our view harmonious analogies between the constitutions of related objects, general laws, etc. which at present totally escape us. In short, if it is founded in truth, its enabling the application of mathematics to chemistry, cannot but be productive of material results.5

The foregoing statement might almost be taken for a prophetic descrip- tion of the virtues of the laws of definite and multiple proportion.

Whether this idea of numerical simplicity exhibited to Smithson from straight weight analyses suggested to Dalton a similar pattern using equiva- lent weights is a question I willingly leave to those better prepared and more inclined than I to pursue. Guerlac is properly cautious when he states that "if the Fischer-Richter Table was important to Dalton as early as 1803-4, it was not for the data it contained, but for the concepts of equivalent weights and the method of obtaining them." 6 Similar caution requires me to say only that if Smithson's paper had any significance in Dalton's genesis of the atomic theory, it was through Smithson's emphasis on the small numerical fractions expressing chemical composition. This in combination with the idea of equivalents based on the Fischer-Richter tables could have led Dalton to his chemical atomic theory.

5 Loc. cit., pp. 25-26. 5 Loc. cit., pp. 25-26. 6 Loc. cit., p. 547. 6 Loc. cit., p. 547.

THE CRAWFORD LIBRARY OF THE ROYAL OBSERVATORY, EDINBURGH

By D. Alasdair Kemp *

THE CRAWFORD LIBRARY OF THE ROYAL OBSERVATORY, EDINBURGH

By D. Alasdair Kemp *

The author has been told that the Crawford Library in the Royal Obser- vatory, Edinburgh, is not widely known in the United States. As it has been described as being second only to the library of Poulkovo Observatory in the U.S. S. R.1 in its collection of astro- nomical literature, it obviously deserves to be better known. It is hoped that the following notes will bring the Craw- ford Library to the attention of those interested in the history of astronomy.

The author has been told that the Crawford Library in the Royal Obser- vatory, Edinburgh, is not widely known in the United States. As it has been described as being second only to the library of Poulkovo Observatory in the U.S. S. R.1 in its collection of astro- nomical literature, it obviously deserves to be better known. It is hoped that the following notes will bring the Craw- ford Library to the attention of those interested in the history of astronomy.

* Royal Observatory, Edinburgh. 1 Edinburgh Evening News, March 28, 1896. * Royal Observatory, Edinburgh. 1 Edinburgh Evening News, March 28, 1896.

The collection was made by James Ludovic Lindsay, twenty-sixth Earl of Crawford and ninth Earl of Balcarres (1847-1913). The nucleus was the li-

brary of Charles Babbage, the mathe- matician and inventor of calculating machines, and further books were drawn from the Crawford family library at Haigh Hall, Wigan, Lancashire. George Herbert Bushnell, in his Bricks to Books,2 describes the development The name of the observatory is shown as Pultowa. See also Istor. Astr. Issled., Moskva 1959, 5: 111, ? 3.

2 London: Grafton, 1949.

The collection was made by James Ludovic Lindsay, twenty-sixth Earl of Crawford and ninth Earl of Balcarres (1847-1913). The nucleus was the li-

brary of Charles Babbage, the mathe- matician and inventor of calculating machines, and further books were drawn from the Crawford family library at Haigh Hall, Wigan, Lancashire. George Herbert Bushnell, in his Bricks to Books,2 describes the development The name of the observatory is shown as Pultowa. See also Istor. Astr. Issled., Moskva 1959, 5: 111, ? 3.

2 London: Grafton, 1949.

481 481

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