INVENTION OF SODA-WATER

79

On the basis of these observations Macbride proceeded to explain the well-established fact that a diet mainly composed of animal food is apt to produce sea scurvy, the remedy for which is a sufficient supply of fresh vegetables, by assuming that the virtue of the vegetables was due to the evolution of a greater amount of carbonic acid in the process of digestion, the fixed air so liberated in the body counteracting, by its antiseptic powers, putridity in the circulating fluids.

We are not here concerned with the subsequent history of so-called ærated or soda-water, as it came to be called, but it is worth noting that Priestley's account of his process contains one remark which is not without significance in view of latter-day developments. He says:

"I do not doubt but that, by the help of a condensing engine, water might be much more highly impregnated with the virtues of the Pyrmont spring, and it would not be difficult to contrive a method of doing it.'

The manufacture of these waters was subsequently taken up by Priestley's friend and satellite, as he called himself, Richard Bewley, of Great Massingham, an apothecary, and the inventor of the well-known "mephitic julep." Bewley appears to have discovered that the addition of a small quantity of carbonate of soda to the water enabled it to absorb and retain an increased quantity of carbonic acid, and to him, therefore, is due the credit of first making what was long called "acidulous soda-water." The receipt for its manufacture and use, given by Henry of Manchester, is sufficiently quaint to be worth reproduction :

"To prepare Mr Bewley's julep dissolve three drachms of fossil alkali in each quart of water, and throw in streams of

fixed air till the alkaline taste be destroyed. This julep should not be prepared in too large quantities, and should be kept in bottles very closely corked and sealed. Four ounces of it may be taken at a time, drinking a draught of lemonade or water acidulated with vinegar or weak spirit of vitriol, by which means the fixed air will be extricated in the stomach.'

It is hardly to be supposed that the Royal Society Club in 1773 adopted all the social manners and customs of the period. Nevertheless, its members, who were among the most influential fellows of the Society, were evidently greatly impressed with the merits of Priestley's soda-water, since the Council of the Society were moved to reward its discoverer with the Copley Medal.

In making the award on St Andrew's Day 1773, Sir John Pringle, then President of the Royal Society,

said

"For having learned from Dr Black that this fixed or mephitic air could in great abundance be procured from chalk by means of diluted spirits of vitriol; from Dr Macbride that this fluid was of a considerable antiseptic nature; from Dr Cavendish that it could in a large quantity be absorbed by water; and from Dr Brownrigg that it was this very air which gave the briskness and chief virtues to the Spa and Pyrmont waters; Dr Priestley, I say, so well instructed, conceived that common water impregnated with this fluid alone might be useful in medicine, particularly for sailors on long voyages, for curing or preventing the sea scurvy.”

To-day the Copley Medal is regarded as the highest award which it is in the power of the Society to bestow, and certainly no man starts his scientific career by acquiring it—not even for so signal an invention as that of soda-water.

Whilst Priestley was at Leeds a proposal was made to him that he should accompany Captain Cook in his second voyage to the South Seas. It probably arose

IS AWARDED THE COPLEY MEDAL 81

from his connection with the Admiralty in the matter of his invention. He tells us that as the terms were very advantageous he consented to it, the heads of his congregation agreeing to keep an assistant to supply his place during his absence. But Mr Banks informed him that he was objected to by some clergymen in the Board of Longitude, who had the direction of this business, on account of his religious principles. "Whether," said Huxley, in commenting on this circumstance in the course of his speech at the unveiling of the Priestley statue in Birmingham in 1874, "these worthy ecclesiastics feared that Priestley's presence among the ship's company might expose his Majesty's sloop Resolution to the fate which aforetime befell a certain ship that went from Joppa to Tarshish, or whether they were alarmed lest a Socinian should undermine that piety which in the days of Commodore Trunnion so strikingly characterised sailors, does not appear." The appointment was given to Reinhold Forster, a man, as Priestley fully admitted, far better qualified for the position.

CHAPTER VI

Becomes literary companion to Lord Shelburne - Goes abroad-His visit to Paris-His scientific work at

Calne and in London-Continues his theological and metaphysical studies His growing unpopularity— Leaves Lord Shelburne.

PRIESTLEY Continued at Leeds for about six years. Although very happy there he was tempted to leave Mill Hill Chapel to enter the service of Lord Shelburne. How he was regarded by his flock may be gleaned from the addresses which were presented to him on the eve of his departure; these, together with his own farewell letter, are still preserved among the Chapel books of Mill Hill. But a stipend of one hundred guineas a year, and a house which was not adequate to contain a family now increased by the birth of two sons, and with no possibility of making any provision for them in the event of his death, induced him to accept Lord Shelburne's proposals.

Lord Shelburne, afterwards first Marquis of Lansdowne, one of the most enlightened of the many politicians who sought to direct the destinies of this kingdom during the stormy times of the last thirty years of the eighteenth century, had been Secretary of State in Pitt's administration of 1766, but had been dismissed from office in 1768 on account of his conciliatory policy towards America, and at this particular time was living in retirement at Bowood. Under these circumstances his lordship, a man of culture and fond of literature, sought the companionship of some kindred spirit. Through the good offices of Dr Price, a mutual

LORD SHELBURNE

83

friend, he was led to make Priestley so generous an offer-viz., two and a half times his Leeds salary, a pleasant house at Calne in the summer and a house in town during the winter, and a retiring allowance for life should their connection be dissolved-that our philosopher was constrained to accept a position which, despite its perils and possible constraints, was so alluring. The engagement seems to have given satisfaction also to Priestley's friends, if we may judge from the following extract from one of Wedgwood's letters to his partner at Etruria, Thomas Bentley of Liverpool, one of the founders of the Warrington Academy :--

"I am glad to hear of Dr Priestley's noble appointment, taking it for granted that he is to go on writing and publishing with the same freedom he now does, otherwise I had much rather he still remained in Yorkshire." Meteyard, II. 451.

In their political sentiments, and in their views on the great questions which at that time divided parties, the two men had much in common. Lord Shelburne was certainly not unaware of Priestley's political proclivities, and the pamphlet he had written at Franklin's instigation on the American question probably expressed his Lordship's own sentiments. At the same time Priestley was under no obligation to serve Lord Shelburne politically, and there is no evidence that any such service was either expected or rendered. His office was nominally that of librarian, but he had little to do in that capacity beyond arranging and cataloguing the books and numerous manuscripts at Bowood and Lansdowne House and making an index of Lord Shelburne's private papers. Indeed, Lord Shelburne treated him rather as a companion and friend than as a servant, taking him, in the second year of his engage

F