while still in the dukes service, he had published 'A New Method of improving Cold, Wet, and Clayey Grounds,' of which there is no copy in the British Museum or the Bodleian. It may have attracted attention abroad, for the indomitable adventurer next turns up in Sweden in 1742. Here he represented himself as a physician, prescribed successfully for the king, and was actually appointed one of the physicians in ordinary, but soon incurred the suspicion of quackery, and fell back upon his old trade of practical agriculturist. He published in 1745 'An Essay on the Improvement of Swedish Agriculture,' which was suspected of being a translation been from the English ; and was entrusted with the direction of a model farm at Allestad. This was alleged to have deteriorated under his management, and the precariousness of his appointment may perhaps have driven him to engage in political intrigue. Sweden, under the weak rule of King Frederick, was at the time distracted by the contending factions of the 'Hats' and the 'Caps,' former under French influence, the latter inclining to England. An unquiet spirit like Blackwell would be prone to fish in these troubled waters, and as his political relations were chiefly with the English party, the representatives of his own country might well seek to make a tool of him. In March 1747 he presented himself to the king with a mysterious verbal communication purporting to come from the Queen of Denmark (Louisa, George II's daughter), vaguely hinting at a large sum of money to be bestowed on condition of altering the succession to the exclusion of the infant crown prince. The king, at first referred Blackwell to two of his confidants, but on the following day, becoming alarmed, disclosed the incident to his ministers, who immediately arrested Blackwell. The latter admitted making the communication, and declared that he had been prompted to do so by an anonymous letter which he had destroyed, and the source of which was unknown to him. To extract further revelations he was cruelly tortured. He long withstood his sufferings with the greatest constancy, and although he ultimatelv succumbed, he revoked his confession, and it is difficult to ascertain what it really was. It certainly implicated no other person, for no one else was proceeded against. The sentence of the judges, if correctly cited, condemned him for 'designing to alter the present constitution, and to render the crown absolute to set aside the present established succession ; and to procure large sums of money to enable him to execute these schemes.' It was insinuated that Adolphus Frederick, the next heir, was to have been poisoned, that 'a certain young prince,' the Duke of Cumberland, was to have been put upon the throne, and that Adolphus Frederick's son, afterwards Gustavus III, was to have been indemnified by a principality in Germany. On these charges, of most if not of all of which he was unquestionably innocent, Blackwell was condemned without any public trial to be broken on the wheel, a punishment commuted into decapitation. He met his fate on 9 Aug. 1747 with remarkable fortitude, apologising for laying his head on the wrong side of the block on the ground that it was the first time he had ever been beheaded. The speech he endeavoured to address to the bystanders was drowned in the roll of drums, and a paper published in his name is probably spurious. The real object and secret springs of his intrigue remain a mystery. Some have thought that it was a device of his own to gain the king's favour and magnify his own importance, and that the alleged anonymous letter was a the figment. Others deem him the instrument of a foreign court, probably England. The 'Hats' regarded him as an agent of their adversaries; the 'Caps' insisted that he had been made the stalking-horse of a fictitious plot, Not a few suspected that he had been ensnared by the minister Tessin, who was supposed to be jealous of his influence, and certainly took the leading part in his torture and execution. Blackwell is universally represented as meddlesome, pragmatical, and loquacious, and the theory that his plot was wholly concocted by himself would appear the most plausible, but for the evident pains taken by the English government to vindicate itself at his expense. According to the correspondent of the 'Bath Journal' Blackwell was an excellent scholar in his youth. His eminent talents were marred by want of principle and unsoundness of judgment, but he must have possessed enterprise, courage, and versatility.
[Gent. Mag. 1747. pp. 424-6 ; A Genuine Copy of a Letter from a Merchant in Stockholm to his Correspondent in London (London, 1747); Chalmers's Dictionary, art. 'Blackwell (Elizabeth); Credercreutz, sverige under Ulrica, Eleonora, ich Frederic I (1821): Fryxell, Berättelser ur Svenska Historien, pt.xxxvii., Stockholm, 1868. The proceedings of the tribunal which condemned Blackwell were sealed up by the order of Count Tessin, and remained unexamined for thirty-three years, when Gustavas III deposited them in the public archives. Their contents were first divulged in 1846, in an essay contributed to the newspaper Frey, by N. Arfvidsson, upon which Fryxell's circumstantial and interesting narrative is mainly founded.]
