ON THE MANUFACTURE OF GLAS* FOR OPTICAL INSTRUMENTS. 165 



most made use of in the Anatomical Laboratories of Paris, belongs to 

 Dr. Doyere, who promises to be to zootomy one of its most distin- 

 guished observers. According to this process,* an aqueous solution of 

 bi-chromate of potass is propelled into the vessels ; after a short time, 

 in the same manner and into the same vessel, an aqueous solution of 

 acetate of lead is injected. This injection is made quite cold in a 

 most easy and economical way, and the finest vascular networks are 

 instantly coloured of a beautiful sulphur- yellow hue. I have also made 

 several trials with a solution of caoutchouc, which gives great flexibility 

 to the vessels. 



Explantion of the Figures, Plate V, Div. 1. 



Fig. a. Represents the small Syringe used by M. Rusconi for his injections. 



This instrument should be made of silver ; it is ten centimetres long by two in 

 diameter ; its free extremity, which is received in the small tube, is conical, thirty- 

 two millimetres long, and should be made of gold. This syringe has a ring on 

 which the index or middle fingers rest, when the piston is about to be pushed for- 

 ward. The end of the syringe, which is of gold, has very thin and at the same time 

 resisting walls ; the opening at the extremity should be as large as possible. 



We cannot give here figures of the quills of the quail or partridge made use of by 

 M. Rusconi. When it is required to inject the sanguiferous system of tadpoles or 

 salamanders, the smallest tubes are used. 



Fig. b. Represents the lymphatic vessels of a portion of the rectum of a sala- 

 mander, a continuation of the small intestines. This drawing is a most faithful 

 copy, drawn by M. Rusconi from an anatomical preparation, in which the lymphatics 

 had been filled with a reddish coloured fluid, and the arteries distended by a sub- 

 stance of a white colour. On attentive examination of this figure, may be distin- 

 guished, by their white tint, the arteries in the centre of the lymphatics, and the 

 branches (ramuscules) of these same lymphatic vessels. 



XXVII. ON THE MANUFACTURE OF GLASS FOR OPTICAL INSTRUMENTS. 



MR. A. BOURNE of Chillicothe, Ohio, has addressed a letter to the 

 Editors of the American Journal of Science and Arts, which is inserted 

 at p. 207 of the number for January, 1841, in which after alluding to 

 the decline of this art in proportion to the progress of the other arts in 

 England, and to the results obtained by the Committee of the Royal 

 Society of London in 1824, and the members of the Board of Longi- 



* For a more detailed account of this process, consult the Microscopic Journal, 

 Vol. I, p. 156. 



