9M 



Intelli<rence and Miscellaneous Articles. 



Improved Form of Messrs, WiWs and Farrentrapp's Apparatus. 



The only inconvenience I have found in the process proposed by 

 Drs. Will and Varrentrapp for the estimation of nitrogen in organic 

 bodies, is the liability of the liquid in the condenser being thrown 

 back into the combustion-tube by sudden absorption taking place, 

 or fi'om too violent an evolution of the gases, part of it being ejected 

 from the other extremity of the condenser. So well-aware were its 

 authors of this inconvenience, that they recommend in the analyses 

 of substances rich in nitrogen the introduction of sugar, or some 

 other body abounding in carbon, into the combustion-tube, I have 

 found that the necessity of this addition, which is of course open to 

 many objections, may be entirely avoided by using a condenser 

 nearly three times as large as that generally employed, and by sur- 

 mounting each of the bulbs with another bulb of about half its ca- 

 pacity. The opening between the bulbs should be very wide, they 

 being run into one another in the same manner as in the lower bulbs 

 of Liebig's potash apparatus. With a condenser of this description, 

 the large bulbs being 1| inch in diameter and about 4 inches aj)art, 

 I have never experienced the least accident, nor am I compelled to 

 pay that constant attention to the progress of the combustion which 

 Drs. Will's and Varrentrapp's condenser usually requires. 



Fig. 3. 



Mr. Taylor also exhibited a small instrument for holding Da- 

 guerreotype plates during the process of washing off. It consisted 

 of two pieces of brass or plaited wire fitted into a wooden handle. 

 One of the wires is bent into the form of an acute triangle, its base 

 being slightly turned up, so as to form a ledge for the silver plate 

 to rest upon. The other wire is placed between the sides of the 

 triangle curved, so as to form a spring, which rests upon the top 

 of the plate, and keeps it in its place. By inserting the fore-finger 

 in the loop of the spring, the plate may be shaken violently without 

 becoming dislodged. 



Fig. 4. 



From the Proceedings of the Chemical Society. 



