jlO PHILOSOPHICAL TRANSACTIONS. [aNNO 1684. 



seen on its surface. Moreover, the congeries of excretory vessels, of whicli 

 the fleshy part of the kidneys is composed, was more bulky than usual. Of the 

 large glands or vesicles appendant to the excretory vessels some were filled with 

 dark-coloured, corrupted blood ; others with urine, or gravel, or tartareouB 

 matter. From this simple though morbid structure, it evidently appears (the 

 author thinks) that the chief parts of the kidneys, besides the arteries and veins, 

 are the glands and pelvis; which last being lengthened out into ureters, re- 

 ceives the urine from the glands by their excretory vessels, and gradually trans- 

 mits it to the bladder. The preternatural enlargement and appearance of the 

 glands (in this case) were owing to the urinary secretion being prevented from 

 getting into the pelvis: whence it collected and remained stagnant within them. 

 The same thing happens (the author observes) in other glandular parts, when 

 diseased ; and particularly in the liver, the glandular acini of which are not un- 

 frequently so distended with bile, serum, or tartar, as to put on a vesicular ap- 

 pearance.* 



A Letter from Mr. Charles Leigh, of Brazen-Nose College in Oxford, to Dr. 

 Robert Plot, Sec. R. S. N° l6o, p. 60Q. 



The specimens of the water of natron and Nitrian nitre -f- you gave me, I have 

 found to agree exactly with the descriptions which the ancients give of it. For 

 the better understanding of the writings of the ancients concerning it, I shall 

 in the 1st place show whence nitre has its denomination. In the 2d, the differ- 

 ent names which ancient authors ascribe to it. In the 3d, the different places 

 whence it comes. In the 4th, a description of it as it is when a compositum. 

 In the 5th, the number of its principles when chemically resolved. In the 6th, 

 the rise of them. In the 7th, its separation from the water of natron. In the 

 8th, its use in physic. In the Qth, in agriculture and mechanics. In the 10th, 

 wherein it differs from sal ammoniac. In the 1 1th, from saltpetre. 



All nitre took its name from a town in Egypt called Nitria. It is variously 

 named by the ancients sal ^gypti, nitrum rubrum, spuma nitri, halmiraga, 

 &c. &c. 



It is found in Armenia, Africa, ;{: ^gypt, &c. 



• The reader is referred to volume i, pp. 322-324 of this Abridgment, for a detail of Malpighi's 

 observations on the structure of the hver and kidneys. 



+ By Nitrian nitre is here understood the mineral alkali combined with the carbonic acid (carbonate 

 of soda) and mixed with various impurities, not the neutral salt nitre (nitrate of potash.) 



J That of Tripoli in Barbary, of which a description was given by the late Dr. Donald Monro, in 

 the 6 1st volume of the Philosophical Transactions, is remarkably pure. It is also met with in con- 

 siderable quantities in Hungary, and in some of the provinces of Russia. 



