also, the German name, the earliest mention of which occurs perhaps in the writings of Basilius Valentine, denoted at first every kind of ferrugi, nous earth employed by the potters for painting. Thus Schwenkfeld gave the name of Braunstein and Braunfarbe to a kind of bloodstone.*

For a long time the manganese imported from Piedmont was in Germany accounted the best; and therefore was much sought after by the artists of Nuremberg. Afterwards, a kind brought from Perigord, a place in Guyenne, and named pierre de Perigueux, or lapis petracorius, was highly esteemed. Wallerius gives this as a peculiar species; and in my opinion he is right. Its distinguishing characters are, that it resembles a burnt coal or cinder; has a somewhat shining surface, and on the fracture appears to be finely striped and a little coloured. A piece which I have in my possession exhibits all these marks. This species has been mentioned by very few of the new mineralogists. Germany, however, for some centuries past has employed its own manganese, which even

* Stirpium et fossilium Silesiae catalogus, Lipsiae 1600. 4. p. 381. In Albinus's Meissnischer Chronik, 1589, fol. ii. p. 151, the following words occur: Die Glassköpf von der Platten geben sonderlich den Töpfern eine gute kesselbraune Farbe, daher ich achte, dass sie von etlichen auch Farbesteine genennet werden.

↑ Systema mineralog. i. p. 330. Compare Pomet's Materialist, Leipzig 1717, fol. p. 752. Lemery Materialien-Lex. Leipz. 1721, .fol. p. 611.

in the time of Biringoccio was sent, as an article of commerce, to Italy.*

That in our times a peculiar metal called magncsium, or regulus magnesii, has been found in manganese, is too well known to require much notice. I shall however remark, that Ignatius Gottfried Kaim, in his Dissertation de metallis dubiis, printed at Vienna, in 1770, first mentioned this regulus, which was afterwards proved in a fuller manner by J. Gottlob Gahn, Bergman, and Ilseman. A Frenchman named de la Peirouse is said to have also found it, in a native state, in an iron-mine in the county of Foix.†

PRINCE RUPERT'S DROPS. LACRYME VITREE.

Ir is more than probable that these drops, and the singular property which they possess, have been known at the glass-houses since time immemorial. All glass, when suddenly cooled, becomes brittle, and breaks on the least agitation. On this account, as far back as the history of the art can be traced, a cooling furnace was always constructed

* Pirotechnia, 1550, 4to. p. 36. b.

+ See Leonhardi's additions to Macquers chemischen Wörterbuche, 1788. i. p. 572.

close to the fusing furnace. A drop of fused glass falling into water* might easily have given rise to the invention of these drops; at any rate this might have been the case in rubbing off what is called the navel.† It is, however, certain that they were not known to experimental philosophers till the middle of the seventeenth century. Their withstanding great force applied at the thick end, and even blows; and on the other hand, bursting into the finest dust when the smallest fragment is broken off from the thin end, are properties so peculiar that they must excite the curiosity of philosophers, and induce them to examine these effects, especially at a time when mankind, in general, exert themselves with the greatest zeal to become better acquainted with the phænomena of natural bodies. On this account they have been noticed in almost every introduction to experimental philosophy. To determine the time then in which they were first made known, seems to be attended with little difficulty, but it still remains doubtful by whom and in what country.

* It is not always necessary that the water should be cold: these drops will be formed also in warm water, as well as in every other fluid, and even in melted wax. See Redi's experiments in Miscel lan. naturae curios. anni secundi, 1671, p. 426. They succeed best with green glass; yet I have in my possession some of white glass, which in friability are not inferior to those of green.

+ The navel, in German nabel, is that piece of glass which remains adhering to the pipe when any article has been blown, and which the workman must rub off. These navels, however, are sel dom in so fluid a state as to form drops.

It appears certain that the first experiments were made by philosophers with these drops, in the year 1656. Monconys,* who travelled at that period, was present when such experiments were made at Paris, before a learned society, who assembled at the house of Mommor, the well-known patron of Gassendi; and the same year he saw similar experiments made by several philosophical persons at London. He tells us expressly that Chanut, the Swedish resident, procured glass drops for the first Parisian experiments; and that these drops were brought from Holland.

It appears, therefore, that the first glass drops were made in Holland; yet Montanari,† who was professor of mathematics at Bologna, says that the first were not made by the Dutch but by the Swedes. The grounds, however, on which he rests his assertion are exceedingly weak. Because a Swedish resident procured those used for the first experiments, it does not follow that they were made at Swedish glass-houses, especially as it is positively said that they were brought from Holland. It was indeed stated so early as 1661, by Henry Regius or Van Roy, professor at Utrecht, that

* Journal des voyages de M. Monconys, Lyon 1666, 4to. ii. p. 162. J'ai appris que M. Chanut resident de Suede avoit fait voir des larmes de verre vert toutes solides venuës de Hollande.

↑ Speculazioni fisiche del dot. Geminiano Montanari Modanese, sopra gli effetti di que' vetri temprati, che rotti in una parte si risoluono in polvere. In Bologna 1671, 11 sheets 4to. p. 41.

H. Regii Philosophia naturalis, Amstelodami 1661. 4to. p. 515: Adferuntur huc ad nos e Suecia globuli vitrei caudati - In the

these glass drops came from Sweden; but may not this have been a lapse of memory, occasioned by the circumstance that the first drops used by the natural philosophers of Paris were procured by a Swedish resident?

Monconys, whose relation indeed bears evident marks of great haste as well as credulity, calls Chanut Resident de Suede, and seems to have consi dered him as a Swedish resident at the French court; an opinion in which he has been followed by many literary men.* But Pierre Chanut was French resident at Stockholm, and at that time so well known that Monconys could hardly be unac quainted with his quality. He was resident from the year 1645 to 1649; and he was afterwards envoy for adjusting the disputes between Sweden and Poland, which were to be settled at Lubec. He

Amsterdam edition, by Elzivir, 1654, 4to, which in the title is called the second, these glass drops are not mentioned.

* In the German translation of Monconys' Travels Chanut is styled resident of his Swedish majesty. In the Miscellanea Naturae. Curios. already quoted, where the account of Monconys is translated into Latin, it it said: Intellexi, quod Chanut Residens regni Sueciae vidisset parari lacrymas ex vitro viridi penitus solidas, ex Hollandia advectas. Here then there is a double mistake. Montanari says, p. 41: Primi vetri temprati erano state participate da M. Chanut Residente di Suezia in quella corte, consequently at the French court. J. G. Baier, in his Dissertation de lacrymis seu guttis vitreis, Altorf 1708, 4to. p. 5, says: Anno 1656, Parisiis capta sunt de lacrimis vitreis experimenta, suppeditante eas D, Chanut in aula Regis Galliarum Residente, allatas e Belgio.