45, COENHILL, E.G., AND 122, REGENT STEEET, W., LONDON. 195 



558 Comparative Scales (Baker's) compiled from tables of eminent authorities, for 

 the use of Chemists, Distillers, Brewers, Dyers, Bleachers, Paper makers, British 

 Wine makers, Confectioners, &c., &c. 



It Comprises Specific Gravity Scale, TwaddeH'Sj'Baume's, Cartier's, Gray Lussac's, 

 Saccharometer scale of Ibs. weight per barrel, Extract per barrel, and the Govern- 

 ment Proof Spirit scale. Several percentage scales for Spirits, Acids, Chlorine, 

 Ammonia, Solutions of Potash, Soda, and four comparative Thermometer Scales; viz., 

 De Lisle, Centigrade or Celsius, Fahrenheit, and Reaumur, in all 34 scales, 

 containing a vast amount of most valuable and useful information. Price 2s. each. 



Recent Acts of Parliament in connection with the adulterations of food, drugs, 

 &c., &c., will often necessitate strict investigation; in such matters, therefore, 

 Messrs. Negretti and Zambra cannot too strongly impress upon the minds of their 

 customers the great importance of accuracy in all apparatus used for analysing or 

 testing the purity or strength of the articles under examination. 



For such purposes, N. & Z., from their great experience in this special branch 

 of their trade, can confidently recommend their instruments. 



The various Areometers, &c., &c., used on the Continent to ascertain the 

 density of Liquids, made to order. 



GAUGING INSTRUMENTS, RULES, Ac. See Scales and Rules. 



Specific Gravity of fluid Mercury. The density of this Metal at 39-2 F., is 13-588, 

 according to Kupffer. Hence its Specific Gravity near the point of congelation will be 

 13-694. MESSES PLAYFAIE AND JOULE. 



The Specific Gravity of solid (frozen) Mercury is stated by Kupffer and Cavallo to be 

 about 14-0. 



According to Dufour, the Specific Gravity of Ice is 0-9178 ; Bunsen states it at O91674. 



" Sea Water freezes at 2'5 to C. ; the ice which forms is quite pure, and a 

 saturated solution remains. If water contains Alcohol, precisely analogous phenomena are 

 observed ; the ice formed is pure, and all the Alcohol is contained in the residue." GANOT. 



" M. Despretz by the cold produced with a mixture of liquid Protoxide of Nitrogen, 

 Solid Carbonic Acid, and jEther has reduced Alcohol to such a consistence, that the vessel 

 containing it could be inverted without losing the liquid." 



Lowest artificial cold produced by Chemical Combination, 187 below Zero F. 

 A. S. TAYLOE. 



Ditto ditto 140 C. GANOT. 



Mercury freezes, 37'9 Fah. Kew. Carbonic Acid Gas Solid at 148 below 0, F. 



We are informed that lower temperatures have been recently produced ly Chemical 

 action. 



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