MR. HATCIIETT S EXPERIMENTS ON. L.AC. Qj 



Another phenomenon in thefe inftruments is obfervable ; Phenomenon of 

 it is not new, but it deferves a marked attention in the prefent * ^ e ^ T? °^ 

 enquiry : If the apparent expanfion of water for the fir ft 10° fluid when the 

 of temperature, reckoned from the loweft point in any of the !. n( ? rui " ent IS 

 above inftruments, be denoted by 1 ; then if the inftrument, 

 taken at any temperature, be fuddenly plunged in water of 

 10° higher temperature, the water in ftantly finks a confider- 

 able way, occafioned no doubt by the veffel being extended 

 by the heat betbre the water it contains has time to expand. 

 The quantity of depreffion in the different inftruments was 

 found as under: 



Brown earthen ware finks by being dipped in Table of this de. 



preflion in the 

 different ther- 

 mometers. 



water of 



10° h 



ighei 



• temperature, 



- 



.2 



Queen's ware, 





- 



- 



.3 



Flint-glafs, 



- 





- 



- 



.'2.5 



Iron, - 



- 





- 



- 



.66 



Copper, 



- 





- 



- 



.9 



Brafs, 



- 





- 



- 



1.1 



Pewter, 



- 





- ■ 



- 



1.0 



Lead, 



- 





- 



- 



1.5 



I fubmit thefe facts to the confideration of thofe who feel 

 interefted in the enquiry ; and defire that they may be parti- 

 cularly inveftigated by thofe who maintain that water is denfeft 

 at 40°. 



I remain your's, 



J. DALTON. 

 Mancheftcr, Jan. 10, 180k 



VII. 



Analytical Experiments and Obfervations on Lac. Zty Charles 

 Hatchett, Efq. F. R. S. From the Fhilofaphical Tranfac- 

 tionsfor 180 k 



(Concluded from p. 54.) 



Properties of the colouring Extract of Lac. 



1. VV HEN dry, it is of a deep red colour, approaching to Colouring ex- 

 purplifh crimfon. tract of lac 



2. Being put on a red-hot iron, it emits much fmoke, with a 

 fmell fomewhat refembling burned animal matter, and leaves 

 a very bulky and porous coal. 



3. Water, 



