40 Analyses of Books. £Jan. 



Article VII. 



Analyses of Books. 



Fhilosophical Ti-ansactioiis of the Royal Sucieti/ of London, 



for 1819, Part 1, 



This part contains the following papers : 



I. T/ie Croonian Lecture. — On the Conversion of Pus into 

 Grana!ution\i, or new Flesh. By Sir Everard liome, Bart. 

 V.P.R.S. 



In the last volume of the Transactions, Sir Everard Home 

 endeavoured to explain how coagulated blood became vascular. 

 Carbonic acid gas, he informed us, is extricated at the moment 

 of coagulation. This gas gradually lengthens into a tube, which 

 is immediately covered by a coat, and thus converted into a 

 blood-vessel. He is of opinion that the same process goes on 

 during the conversion of pus into granulations, or new flesh. 

 Pus, he tells us, is analogous to the serum of blood. At first, it 

 contains no globules, but they gradually make their appearance 

 in it whether it remains on the surface of the sore, or be removed 

 upon some other surface. Mr. Bauer has observed that the 

 same formation of globules ttikes place in the serum of blood ; 

 thus showing the analogy between serum and pus. The paper 

 is taken up in describing the appearances which are perceived 

 upon the surface of a healing sore, when left for about a quarter 

 of an hour exposed to the atmosphere. The coating of pus 

 coagulates, globules of carbonic acid gas make their appearance 

 in it. These are speedily converted into numerous anastomosing 

 vessels filled with red blood. 



II. 0)1 the Laics vihich regulate the Absorption of Polarized 

 Light 1)1/ Dotihlij Refracting Crystals. By David Brewster, 

 LL.D. F.R.S. Lond. and Edin. 



If to one side of a rhomboid of colourless calcareous spar we 

 fasten a circular aperture of such magnitude that the two images, 

 of it appear distinctly separated when viewed through the spar, 

 we shall find that when the spar is exposed to common light, 

 the two images are equally colourless, and of the same intensity 

 in all positions; so that the ordi)iarij image contains half the 

 quantity of transmitted light, and the extraordinary image like- 

 v»'ise half the quantity of transmitted light. When the rhomboid 

 is exposed to polarized light, the intensities of the two pencils 

 are together equal in every position to the whole transmitted 

 light. Hence the rays which leave one of the images by a change 

 ■of azimuth pass over into the other image. 



When the same experiment is tried with certain specimens of 

 yellow calcareous spar, the results are difi^erent. The two images 

 ditfier both in colour and intensity ; the extraordinary image 



