148 On the Chemical Nature of Ants. 



ter<; of reference are the fame in both, where they can be ap - 

 plied. 



The bar A^, of which the fide B C is of iron, and the other 

 DE of zinc, is about one inch broad, a quarter of an inch 

 thick, and eight inches in length. It is firmly fixed, at the 

 lower extremity I, to a board :i,b,c,d, made of mahogany. 



On the application of heat, this bar, by the fuperior ex- 

 panfion of the zinc, is inclined at the top towards B. In the 

 upper end of the bar there is a pin (feen at A, fig. 3.) which, 

 goes into the fork-like opening L of the index LM (fig. i.), 

 and carries the Ihort end of this index along with it; confe- 

 quently the long end is carried along the fcale from 0° to- 

 wards 100'^. 



When the inftrument is expofcd to a lower temperature, 

 the movement is exadly the reverfe of what I have been de- 

 fcribing. 



Beneath the index LM are two others on the fame axis G, 

 ©ne of which can be carried towards the right, and the other 

 towards the left, by means of a pin which goes through the 

 firft-mentioned index at H. By this means, the greateft and 

 lowed degree of temjierature that occurs from the time the 

 thermometer is fet or adjufted till it be again confulted, is 

 accurately marked. 



In adjufting the thermometer for obfervation, all that is 

 necelTary is to bring the two Imall indexes immediately be- 

 low the broad one. As the lafl-mentioned one is moved 

 backwards or forwards by variations of temperature, it carries 

 one or other of the fmall ones along with it, by means of the 

 pin H, leaving one of them at the higheft and the other at 

 the lowed degree that may have occurred from the laft lime 

 of adjuftmeat. 



The face of the upper part of tlie inftrument is covered with 

 a glafs door, the haigis of wliich are at N and O. 



Thf; gieafeft range of any thermometers of this kind which 

 I have yet made, is from lo^ below to 100'' above o\ This 

 inftrument proves verv accurate in its indications. 



XXVI. Menio'.r on the Chemical Nature of A7its, and the 

 fimiiltaneous Exflence of two Vegetable Acids in thefe In- 

 fers. Bj A. F. Fou ucROY *, 



ift. oO much ha? been already faid in regard to ants and 

 their acid, that it appears nothing more remains to be added 



* Fiijm /bir.ales du MnJ'rum Njiicnal, No. 5. 



on 



