876 Traxsactioxs of tub Americax Ixstttute. 



information will interest calico printers. A fact of more cjeneral 

 interest is that fluoride of potassium will remove ink stains from 

 cloth. 



Detection of Aksenical Pigments. 

 Durin<^ the first five months of this year no less than eicrht cases of 

 accidental poisoning^ by these pigments have occurred at Xuremburg. 

 M. Puscher advises the use of liquid ammonia for the detection of 

 such pigments, all of which, he says, are soluble therein, exhibiting a 

 blue coloring solution, if copper is at the same time present ; he further 

 states that on the evaporation of the ammonia there remains a dirty 

 greenish colored precipitate of the arsenite of oxyd of copper. His 

 advice is to paint some "white paper wifch this solution in ammonia, 

 which painting, when dry, if arsenic be present, will exhibit a dirty 

 greenish color ; but if, after drying, a blue color appears to have been 

 imparted to the paper, the pigment is quite free from arsenic, and 

 only consists of a copper compound. There are several green and 

 blue pigments of this kind, which are all soluble in amponia, except 

 such adulterations as do not essentially belong to the pigment itself. 



Pegeneration of Limbs. 

 M. Philippeaux's experiments on the regeneration of limbs have 

 been repeated by Milne Edwards, who has described some new results 

 in a communication to the French Academy of Sciences. His early 

 experiments on reptiles prove that if the limbs of a newt be cut ofi', 

 the scapula or ilium being left behind, the limbs will be reproduced ; 

 but if the scapula is removed, the limb is never reproduced. His 

 recent experiments with fishes give similar results. If the fin rays 

 of a fish be cut off, they will be reproduced ; but if the part corres- 

 ponding with the scapula be removed, no reproduction will take 

 place. 



PiiOTOGRAniic Aid in Surveying. 



The following is an extract from the report of Pegnault, Fizeau, 

 and Abbadie to the French Academy of Sciences upon an ingenious 

 invention by the late Mr. A. Chevalier, which is destined to become 

 of great service in the art of surveying: 



When Daguerre first employed the camera for the purpose of 

 fixing images upon a metal plate, Arago at once suggested that 

 topography might borrow from photography its rapid i)jeans of 

 registration. The view taken by this great physicist gave rise to 



