VOL. LXXVI.] 



PHILOSOPHICAL TRANSACTIONS. 



07 



having first reduced them, in the above-mentioned manner, to their best degree 

 of strength. He was also desired to ascertain how much snow he added ; for as 

 their strength was determined before they were sent out, it would thus be known 

 what was the best strength of these liquors for frigorific mixtures. 



All these bottles were numbered with a diamond ; and as I shall sometimes 

 distinguish them by these numbers, and as it may be of use to those who may 

 consult the original, I have added the following list of these bottles, with their 

 contents. 



N^ 



168 

 27 



103 



28 



8 



151 

 142 

 139 

 141 



143 



72 

 171 



Liquors mentioned in Art. 3. 



Weight of 

 marble which 

 they dissolve 



Spec. grav. 

 at 60° of 

 heat. 



Spirit of nitre 



Deplilogisticated spirit of nitre 



Diluted oil of vitriol 



Equal weights of N° 168 and N° 103 



Very highly rectified spirit of wine „ 



Liquors mentioned in Art. 2. 



Strong oil of vitriol , 



Spirit of nitre 



Some of the same diluted with twice its weight of water. 



Dephlogisticated spirit of nitre 



Some of the same spirit of wine as in N° 8 diluted with 



weight of water 



Diluted oil of vitriol for comparing the thermometers 



Oil of vitriol of about the usual strength, but the exact strength 



not known, intended to refresh the former when too weak 



H 



itsl 



.582 



.53 



.654 



.98 

 .525 



.53 



.629 



1.4371 

 1.4040 

 1.5596 



.8195 



1.8437 

 1.4043 



1.4033 



Professor Braun says, that by mixtures of snow and spirit of nitre he sunk, 

 thermometers filled with oil of sassafras, and some other essential oils, to 

 — 100° or — 124°; and that, by the same means, he sunk thermometers filled 

 with the highest rectified spirit of wine to — 148°. Though there seemed great 

 reason to think, from Mr. Hutchins's experiments, that there nmst be some 

 mistake in tiiis ; yet, as it was possible that the essential oils, and even spirit of 

 wine of a strength much different from that with which Mr. Hutchins's thermo- 

 meters were filled, might follow a considerably different progression in their 

 contraction by great degrees of cold, I sent a thermometer filled with oil of 

 sassafras, and two others with spirits of wine. One of these last was filled with 

 the highest rectified spirits I could procure, its specific gravity at 6o° of heat 

 being .8185; the other was intended to be filled with common spirits, though 

 from circumstances I am inclined to suspect that also to have been filled with the 

 best spirits. Besides these, there was sent a mercurial thermometer, accurately 

 adjusted, according to the direction of the committee of the r. s., printed in the 

 67th vol. of the Transactions; and also the two spirit thermometers used by Mr. 

 Hutchins, which were filled with spirits whose specific gravity was .8247. 



These thermometers were compared together by exposing them to the cold, 



VOL. XVI. O 



