VOL. XVH.], /LJ PHILOSOPHICAL TRANSACTIONS. 5*^06 



lament its loss, as I have reason to believe it was a good medicine, from its 

 strong aromatic smell ; which is much wanting in our testaceous powders. 



As to the third ; the purpura of the ancients* is well made out and figured by 

 Fabius Columna : and it is one of the most common murices of the Mediter- 

 ranean. In this he could not be much mistaken, because he somewhere men- 

 tions heaps of those shells, where the ofHcinae purpuras anciently were ; and 

 also from the purple sanies the fish yields of itself. He mentions one or two 

 more species of turbinate snails, to be found in the Mediterranean, which yield 

 a purple juice. Upon the whole, it is indifferent, what sort of shell we use in 

 the shops, if it is to be calcined, provided it be a sea-shell. Nor do I find 

 either Dioscorides or ^tius distinguish between the ostrea purpura or buccinum 

 calcined ; but they ascribe to them all the same caustic virtue ; possibly some 

 one species may have it in a higher degree, as the various sorts of lime-stone, if 

 calcined, differ in strength. 



Though the species of shell or purpura be scarcely known to our shops at this 

 day, yet the use of the purple juice has been, by tradition at least, transmitted 

 down to our times, and kept as a secret even in these islands, till Mr. Cole dis- 

 covered and published it. Sir Robert Southwell, now the president of the R.S., 

 told me many years ago, that his own mother in Ireland was famous for marking 

 handkerchiefs with the juice of fish ; which mark would never wash out. And 

 the learned Mr. John Beaumont informs me of a passage in Beda's Ecclesiasti- 

 cal History, relating to the purple, as a thing known in his time, viz. 1. 1, c. 1 ; 

 from whence it appears that the purple trade of dyeing was used in England, and 

 very much valued. Of Mr. Cole's you have a cut in the Philosophical Trans. 

 N° I78.'f' And fig. 5, pi. 12, represents the true purpura of the ancients, by 

 the Italians called Gerusolo. 



Extract of a Letter from Mr. ^nth. Van Lemvenhoeck, concerning Animalcules 

 found on the Teeth; and on the Scaliness of the Shin, &c. N° 1Q7, p. 646. 



I have often endeavoured to discover animalcules in spittle, but in vain : but 

 examining a kind of gritty matter from between my teeth, and mixing it some- 

 times with rain-water, and sometimes with spittle, both which before had no 

 animalcules, I then discovered with admiration a great number of very small 

 ones moving ; also a few larger ones, having a very strong and swift motion in 

 the water, like eels. A second sort, much more numerous, turned themselves 

 round like a top, and moved sometimes in a spiral manner. A third sort sonle- 



* Murex. Trunculus. Lin. 



+ Seep. 254 ef. this volume } also pi. 8, fig. §, 10, 11, 12, 13. 



