Pope Clement XIV dies

His work was hardly accomplished, before Clement XIV, whose usual constitution was quite vigorous, fell into a languishing sickness, generally attributed to poison.

No conclusive evidence of poisoning was ever produced. The claims that the Pope was poisoned were denied by those closest to him, and as the Annual Register for 1774 stated, he was over 70 and had been in ill health for some time.
Clement XIV expired on 22 September 1774, execrated by the Ultramontane party, but widely mourned by his subjects for his popular administration of the Papal States.
The Catholic Encyclopedia (or the 1876 Encyclopædia Britannica) opines that:
no Pope has better merited the title of a virtuous man, or has given a more perfect example of integrity, unselfishness, and aversion to nepotism. Notwithstanding his monastic education, he proved himself a statesman, a scholar, an amateur of physical science, and an accomplished man of the world. As Pope Leo X (1513–21) indicates the manner in which the Papacy might have been reconciled with the Renaissance had the Reformation never taken place, so Ganganelli exemplifies the type of Pope which the modern world might have learned to accept if the movement towards free thought could, as Voltaire wished, have been confined to the aristocracy of intellect. In both cases the requisite condition was unattainable; neither in the 16th nor in the 18th century has it been practicable to set bounds to the spirit of inquiry otherwise than by fire and sword, and Ganganelli's successors have been driven into assuming a position analogous to that of Popes Paul IV (1555–59) and Pius V (1566–72) in the age of the Reformation. The estrangement between the secular and the spiritual authority which Ganganelli strove to avert is now irreparable, and his pontificate remains an exceptional episode in the general history of the Papacy, and a proof how little the logical sequence of events can be modified by the virtues and abilities of an individual.
Jacques Cretineau-Joly, however, wrote a critical history of the Pope's administration.

There is no question of the legality of the pope's act; whether he was morally culpable, however, continues to be a matter of bitter controversy. On the one hand, the suppression is denounced as a base surrender to the forces of tyranny and irreligion, an act of treason to conscience, which reaped its just punishment of remorse; on the other hand, it is as ardently maintained that Clement acted in full accord with his conscience, and that the order merited its fate by its own mischievous activities which made it an offense to religion and authority alike. But whatever the guilt or innocence of the Jesuits, and whether their suppression were ill-advised or not, there appears to be no ground for impeaching the motives of Clement, or of doubting that he had the approval of his conscience. The stories of his having swooned after signing the brief, and of having lost hope and even reason, are too absurd to be entertained. The decline in health, which set in shortly after the suppression, and his death (on the 22nd of September 1774) proceeded from wholly natural causes. The testimony of his physician and of his confessor ought to be sufficient to discredit the oft-repeated story of slow poisoning.