11 



heart's action in carp, after being fully exposed by opening into the 

 pericardium without any injury being done to the brain or spinal mar- 

 row, Mr. Clift next passed a hot wire from the tail to the occiput of 

 a carp of the same size, so as to destroy its spinal marrow ; and he 

 found that the action of the heart was quickened for two or three 

 beats, but then resumed the same rate of pulsation as before, although 

 the voluntary muscles had lost their power and did not contract when 

 a stimulus was applied to them. 



After several repetitions of this experiment, with various modifica- 

 tions in the mode of conducting it, the author arrives at the follow- 

 ing results : 



1st. That the muscles of the body of a carp can be thrown into 

 powerful action four hours after the brain and heart are removed. 



2dly. That those muscles lose all power as soon as the spinal mar- 

 row is destroyed. 



3rdly. That by exposure of the heart to water in which the fish is 

 allowed to swim, the action of the heart ceases sooner than in air. 



4thly. That whether the heart is exposed or not, its action conti- 

 nues long after the brain and spinal marrow are destroyed ; and still 

 longer when the brain is removed without previous injury to its sub- 

 stance. 



Sthly. That the action of the heart is in general accelerated for a 

 few beats by injuries to the brain or spinal marrow ; but that de- 

 stroying the spinal marrow after the brain has been separated ren- 

 ders the action of the heart slower for a few beats. 



Some Experiments and Observations on the Colours used in Painting 

 by the Ancients. By Sir Humphry Davy, LL.D. F.R.S. Read 

 February 23, 1815. [Phil. Trans. 1815, ;>. 97.] 



Beside the use which may be made of what remains of ancient 

 paintings as models for imitation, the author has endeavoured to 

 reap the further advantage of making us acquainted with the nature 

 and chemical composition of their colours ; for though the works of 

 Dioscorides, Vitruvius, and Pliny contain descriptions of many sub- 

 stances used by the ancients as pigments, it is only by experiment 

 that the subjects of which they speak can be identified. 



The author's experiments have been made upon colours found in 

 the baths of Titus, in the rums called the baths of Livia, and other 

 ruins of ancient Rome, and in the ruins of Pompeii. Some of these 

 colours had been discovered in vases beneath the ruins of the palace 

 of Titus, and were found to be the same as those used in various 

 fresco paintings of the palace. In one large vase, discovered about two 

 years since, there were found, among other colours, three different 

 kinds of red, one approaching to orange, another dull red, and a third 

 purplish red. The first was minium, the second and third proved to 

 be both ochres of different tints. Another red found in various fresco 

 paintings differed from those found in the vase, and proved to be ver- 

 milion. This substance, called by the Greeks Ktrrufiapi, was known 



