612 ANNUAL RECOKD OF SCIENCE AND INDUSTRY. 



so completely that only the finest touches require the hand 

 of an artist. The essential part of the apparatus is claimed 

 to involve an entirely new mechanical contrivance. 9 C, 



t/ime, 1873, 88. 



I amsler's planimeter. 



The planimeter of Professor Amsler, of Schaffhausen, ordina- 

 rily called the polar planimeter, is, of all the instruments of 

 this class at present known, by far the most simple, the most 

 commodious, and least expensive, and is deserving of a wide 

 introduction among American draughtsmen. It is composed 

 of two metallic rules joined together at a pivot, and, connected 

 at right angles to them at each end, a metallic point. In the 

 prolongation of one of these rules there is found upon an axis 

 parallel to its direction a wheel whose edge is graduated. 

 In order to measure any plane area, one fastens the extremity 

 of one of the arms upon the paper outside of the perimeter 

 of the figure, in such a way that the end of the other arm can 

 be made to follow this perimeter around its whole length. 

 When this end has returned to its point of departure, the 

 divided wheel has undergone a displacement which is easily 

 measured, and is proportional to the area of the figure that 

 was to be measured. 6 i?, 1873, 509. 



RENDERIXG LAMP-BLACK MISCIBLE WITH WATER. 



According to Kochlin, lamp-black acquires all the proper- 

 ties of India ink, and admits of being incorporated Avith 

 printing colors, after mixing it with ten times its weight of 

 sulphuric acid, of 66 Baume, and washing after twenty-four 

 hours. 9 (7, June, 1873, 92. 



THE INFLUENCE OF THE SUNLIGHT ON OLIVE-OIL. 



Amono; the results of the studies of Morchini on the me- 

 chanical influence of sunlight upon olive- oil, we may men- 

 tion the foUowino^ items that will be of interest to commer- 

 cial as well as scientific men. 1. In one month the sunlight 

 will entirely bleach the oil without changing its specific grav- 

 ity. 2. Oil that has been exposed a month to the sunlight 

 has still the property of thickening under the influence of ni- 

 trous vapors ; but if the exposure last two or three months, 

 it continues fluid under the influence that Avould otherwise 



