390 Scientific Intelligence. [May, 



iron. In many manufactures, bismuth and antimony are added 

 to the tin, and these two metals in proper proportions contribute 

 not a little to the beauty of the results ; that of the French manu- 

 facture containing zinc is not suitable. 



The metallic watering has the property of bearing the blow of 

 a mallet, but not of a hammer ; hence it may be used with 

 embossed patterns, but not with those that are punched. The 

 different coloured shades which we see on the watering depend 

 upon coloured or transparent varnishes, which, when properly 

 polished, set off the beauty of the watering. 



V. Test for Arsenic and Corrosive Sublimate. 



The following method has been proposed by Brugnatelli to 

 discover arsenic and corrosive sublimate in their respective 

 solutions, and to distinguish them from each other. 



We must take the starch of wheat boiled in water until it is of 

 a proper consistence, and recently prepared ; to this is added a 

 sufficient quantity of iodine to make it of a blue colour ; it is 

 afterwards to be diluted with pure water, until it becomes of a 

 beautiful azure. If to this azure-coloured solution of starch 

 we add some drops of an aqueous solution of the oxide of 

 arsenic, the colour changes to a reddish hue, and, finally, is 

 quite dissipated. The solution of corrosive sublimate, poured 

 into the ioduretted starch, produces in it almost the same 

 change with the arsenic ; but if to the fluid discoloured by the 

 oxide of arsenic we add some drops of sulphuric acid, the ori- 

 ginal blue colour is restored with more than its original brilliancy, 

 whilst the colour of the fluid that has been discharged by the 

 corrosive sublimate cannot be restored, either by the sulphuric 

 acid or by any other means. 



VI. On the Magnetizing Power of the Violet Rays of the Solar 



Spectrum. 



The reported discovery of M. Morichini, respecting the 

 magnetizing power of the violet rays, which was scarcely credited 

 in this country, has received the confirmation of Prof. Playfair, 

 as related in one of the late numbers of the Bibliotheque Uni- 

 verselle. He gives the following account of an experiment of 

 which he was a witness, and which was performed by M. Carpe. 



After having received into my chamber a solar ray through a 

 circular opening made in the shutter, the ray was made to fall 

 upon a prism, such as those which are usually employed in 

 experiments upon the primitive colours. The spectrum which 

 resulted from the refraction was received upon a skreen ; all the 

 rays were intercepted except the violet, in which was placed a 

 needle for the purpose of being magnetized. It was a plate of 

 thin steel, selected from a number of others, and which, upon 

 making the trial, was found to possess no polarity, and not to 

 exhibit any attraction for iron filings. It was fixed horizontally 

 on the support by means of wax, and in such a direction as to 



