450 Notices respecting New Books. 



ance ; and as it Involves in our opinion no peculiar difficulty, either 

 theoretical or practical, we trust we shall be considered as acting 

 candidly towards the author in selecting it for examination. 



To prepare nitric acid, Mr. Reid directs the use of equal weights 

 of nitre and sulphuric acid, and recommends that the acid distilled 

 should be condensed in a receiver kept cold by a slender stream of 

 water. Now although in this operation the receiver certainly be- 

 comes slightly warm, yet it is never rendered hot; and we know 

 from direct experiment that within ^^ of the whole quantity of 

 acid contained in the nitre may be procured without the aid of 

 any artificial cooling whatever; when, however, it is required, the 

 plan of placing the receiver in a vessel of cold water is much more 

 simple and easy of execution, and requires much less attention 

 than the mode of cooling recommended by Mr. Reid. In the figure 

 representing the apparatus a flask is employed instead of a proper 

 receiver: now this, on account of its form, must render the appa- 

 ratus liable to accident from unsteadiness ; a common bottle is 

 much better, but a tubulated receiver used with it is greatly to be 

 preferred. 



" The distillation" of nitric acid, says Mr. Reid, p. 54, " may 

 also be conducted in flasks with a long glass tube bent at one end 

 in the manner shown in the figure, or the condensation of the acid 

 may be effected almost entirely in the tube. This is a very con- 

 venient method of conducting the process, and is often preferred 

 to distilling the nitric acid from a retort, though beginners find 

 some difficulty in adjusting the tube. The nitre and the sulphuric acid 

 are first put into the flask, and a thin tube bent at an acute angle, 

 about two inches from one extremity, and a very little less in dia- 

 meter than the neck of the flask, is surrounded with some well- 

 worked clay, and put into it, a small quantity of plaster of Paris 

 being placed over the luting to render it tight." 



The reason for this apparatus being " often preferred," Mr. Reid 

 has not given; nor can we discover any, unless that which is con- 

 fessedly difficult to beginners is peculiarly easy to the initiated. 

 We do however assert, without having tried, and without intending 

 to attempt this process, that it is the most inconvenient which it is 

 possible to devise; a flask is much less proper than a retort, as will 

 occur to any one who will for a moment compare the diameters of 

 the descending tube of the former, with the descending aperture of 

 the neck of the latter: owing to the narrowness of the tube, much 

 nitric acid which condenses, necessarily runs back into the flask, 

 and consequently the process is lengthened. It must be difficult, 

 not only to the beginner but also to the veteran, to fasten the glass 

 tube into the flask with clay ; and to render it secure two lutes are 

 recommended, when in common cases one is sufficient ; a thin tube 

 when bent is extremely apt to break at the angle, more especially 

 when it is to be fastened into two flasks, one of which is unsteadily 

 supported on a ring, and the other equally so on its side. 



In explaining the nature of the action occurring between sul- 

 phuric acid and nitre, Mr. Reid observes : " Every two equivalents 



of 



