180 ANNUAL OF SCIENTIFIC DISCOVERY. 



more simple but more veracious than the poor melodramas of Versailles or 

 the Louvre. Then, every Englishman's portfolio will be a hero's Westminster 

 Abbey ; and a richer reward than star or ribbon will- be conferred on the 

 leader, whose monument would be forever before the eyes of his grateful 

 country. 



Photographic Impressions of Blood- Globules. Photographic views of blood- 

 globules taken by M. Duboscq, of Paris, have lately formed the subject of a 

 microscopic exhibition at the Royal Polytechnic Institution. The globules of 

 the blood of the human race, of animals, of birds, reptiles, and fishes, were 

 shown upon the white curtain. The specimens all exhibited the same gene- 

 ral features, varying only in size and shape. The subject is highly important, 

 not only in a medical, but a judicial, point of view, for all blood-stains could 

 thus be analyzed and be made to assist in eliciting the truth, while, for medical 

 purposes, every disturbance that affects the human economy could thus be 

 scrutinized and remedies suggested according to the appearances indicated. 



OX A PROCESS OF OBTAINING LITHOGRAPHS BY THE PHOTO- 

 GRAPHIC PROCESS. 



Professor Ramsay at the British Association, Glasgow, described a process by 

 which Mr. Robert M'Pherson, of Rome, had succeeded in obtaining beautiful 

 photo-lithographs. The steps of the process are as follows: 1. Bitumen is 

 dissolved in sulphuric acid, and the solution is poured on an ordinary litho- 

 graphic stone. The ether quickly evaporates, and leaves a thin coating of 

 bitumen spread uniformly over the stone. This coating is sensitive to light a 

 discovery made originally by Mr. Niepce, of Chalons. 2. A negative < n glass. 

 or waxed paper, is applied to the sensitive coating of bitumen, and exposed 

 to the full rays of the sun for a period longer or shorter according to the 

 intensity of the light, and a faint impression on the bitumen is thus obtained. 

 3. The stone is now placed in a bath of sulphuric ether, which almost instan- 

 taneously dissolves the bitumen which has not been acted upon by light, 

 leaving a delicate picture on the stone, composed of bitumen on which the 

 light has fatten. 4. The stone, after being carefully washed, may be at once 

 placed in the hands of the lithographer, who is to treat it in the ordinary man- 

 ner with gum and acid, after which proofs may be thrown off by the usual 

 process. Professor Ramsay then proceeded to state that the above process, 

 modified, had been employed with success to etch plates of steel or copper, 

 without the use of the burin: 1. The metal plate is prepared with a coating 

 of bitumen, precisely in the manner noticed above. 2. A positive picture on 

 glass or paper is then applied to the bitumen, and an impression is obtained 

 by exposure to light, 3. The plate is placed in a bath of ether, and the 

 bitumen not acted upon by light is dissolved out. A beautiful negative 

 remains on the plate. 4. The plate is now to be plunged into a galvano- 

 plastic bath, and gilded. The gold adheres to the bare metal that refuses to 

 attach itself to the bitumen. 5. The bitumen is now removed entirely by the 

 action of spirits and gentle heat. The lines of the negative picture are now 

 represented in bare steel or copper, the rest of the plate being covered by a 



