342 Analj/sis of Scientific Books. 



for Dr. WoUastou's scale. Our author seems successful in 

 reconciling the constitution of alum with the former number. 



" It deserves to be remarked (says he), that the analysis of Professor 

 Berzeiius agrees with the supposition that alum contains 

 4 sulphuric acid . . . = 20.0 34.36 

 2 alumina = 6.4 11.00 



1 potash - 6.0 10.30 



23 water =: 25.8 44.34 



58.2 100.00 

 " If we rectify Vauquelin's erroneous estimate of the sulphate of bMjtes, 

 his analysis will also coincide with the above. Alum, therefore, ditters 

 from the simple sulphate of alumina previously described, which consisted 

 of three prime equivalents of acid, and two of earth, merely by Us assump- 

 tion of a prime of sulphate of potash." 



Under Aluminite, he shews that this mineral "^ 



" May be represented very exactly by 



2 primes of acid .... 

 5 alumina . . . 



21 water .... 



Foreign matter . . 



50.0 100.0 



" The conversion of the above into alum is easily explained. When the 

 three primes composing bisulphate of potash come into play, they displace 

 precisely three primes (or atoms) of alumina. Two additional primes of 

 vrater are also introduced at the same time,. by the strong affinity of the 

 bisulphate for the particles of that liquid." 



Subjoined to the article Attraction (Chemical) we were 

 glad to see Dr. Young's ingenious tables of affinity, which 

 have been unaccountably omitted in our large systematic works. 



Caloric is a very elaborate article, and, considering the cir- 

 cumstances under which the dictionary was re-written, it is one 

 which will be read with interest. His division of the subject 

 seems to be clear and comprehensive. 



" Enough has now been said to shew how little room there is to pro- 

 nounce dogmatic decisions on the abstract nature of heat. If the essence 

 of the cause be still involved in mystery, many of its properties and eft"ects 

 have been ascertained, and skilfully applied to the cultivation of science 

 and the uses of life. 



" We shall consider them in the following order : 



" 1. Of the measure of temperature. 



" 2. Of the distribution of heat. 



" 3. Of the general habitudes of heat with the dififerent forms of matter." 



The distribution of heat he subdivides into two parts: 1st., 

 the mode of distribution, or the laws of cooling, and the com- 

 munication of heat, among aeriform, liquid, and solid sub- 

 stances : and, 2dly, the specific heats of ditferent bodies, at the 

 same and at different temperatures. In treating of the third 

 head, the general habitudes of heat with the dififereat forms 

 of matter, he says, 



:■ " The eflfects of heat are either transient or physical ; or permanent and 

 chemical, inducing a durable change in the constitution of bodies. The 

 second mode of operation we shall treat of under Combustion. The first 

 falls to be discussed here ; and divides itself naturally into the two heads, 

 of changes in the volume of bodies while they retain their fornj, and 

 (ihaBges in the state of bodies." ^ 



