Notices respecting Netio Books. 49 



lour of animals depends materially on the same agency, as is proved by 

 the striking difference of colour existing between the animals of the frigid 

 and torrid zone. — Dr. Thomson's System, vol. i. p. 20 j then being 

 substituted for in that case. 



Have not certain bodies the property of absorbing the rays of light, 

 of retaining them for some time, and of again evolving them un- 

 changed, and unaccompanied by sensible heat ? 



Yes. Thus in an experiment of Du Fay, a diamond exposed to the 

 sun and immediately covered with black wax, shone in the dark, on 

 removing the wax, at the expiration of several months. Bodies gifted 

 with this property are called solar phosphori. Such are Canton's, 

 Baldwin's, and the Bolognian phosphori. To the same class belong 

 several natural bodies, which retain light, and give it out unchanged. 

 Thus the sea is occasionally when agitated, a natural solar phos- 

 phorus ; putrid fish have a similar property, and the glow-worm be- 

 longs to the same class." 



Now this question and answer are in the very perfection of pecu- 

 lation ; except the slight transposition of a few words, required by an 

 omission, the whole of both is taken from and forms a part of one 

 paragraph of vol. i. p. 160, of Dr. Henry's Chemistry, beginning 

 "Certain bodies have," &c. and after the words " sensible heat," 

 omitting "yes." In the answer the same paragraph is continued. 



This answer concludes the text of Dr. Graham's chapter on Light j 

 and it will be observed that we have traced about five-sixths of the whole 

 to the various authors from whom they have been literally taken. 

 Such is the case with the text ; and similar practices have been pur- 

 sued with the notes of this chapter. In some instances indeed, but 

 evidently that what has been pilfered may pass for his own, Dr. 

 Graham has actually added the names of the authors to whom he is 

 indebted ; but the pro])ortion is not great : for of the matter of the 

 notes, 52 parts are pilfered, 32 borrowed, and 16 we will generously 

 divide between the author and undiscovered sources. 



After these displays of our author's acts of appropriation, the reader 

 may perhaps doubt whether liis volume really contains any one state- 

 ment which Dr. Graham can fairly claim as his own. We liave how- 

 ever, as we think, discovered some portions of the work, which if they 

 be not original, we are quite sure the real authors will never claim ; 

 and these very remarkable exceptions to the Doctor's general method 

 of proceeding occur under the head of Specific Gravity. 



In page 7 of the Catechism we have the following question and 

 answer : — 



" How do you ascertain the specific gravity of fluids f 



There are several methods by whicli it may be ascertained ; but the 

 best is performed by what is called a gravity bottle, which is a glass 

 bottle with a slender neck, furnished with a ground conical stopper. 

 A gravity bottle, called a " thousand grain bottle," from its contain- 

 ing just a thousand grains of distilled water, is considered the best 

 instrument for determining this point with great facility. The thousand 

 grain bottle is sold together witli a weight, which is an exact coun- 

 terpoise for it, when filled witli distilled water at 60" of Fahrcniieit. 

 A^..S'. Vol. G. No. 31. .Ji/li/ lK'2y. II This 



