878 Acari in Photographic Baths and Chemical Solutions. 



to doubt the judgment of gentlemen who seem to consider a 

 superb telescope inferior to a pound of candles, or a first-class 

 microscope below an arm-chair. With reference to this im- 

 portant class of productions neither commissioners nor ex- 

 hibitors — excepting a few of the latter, such as Smith, Beck, 

 and Beck, with their microscopes — have made any provision 

 by which the quality or use of the objects can be seen. It 

 would, for example, have been very interesting and instructive 

 to compare the performances of undoubtedly first-rate instru- 

 ments, by expensive makers, with cheaper forms by Parkes of 

 Birmingham and other meritorious manufacturers, who have a 

 benevolent, and we trust to themselves profitable, regard for 

 the poorer student's purse. This want will be felt with regard 

 to articles whose use is well known, but when we come to such 

 novelties as the chronographs in the French dapartment, special 

 arrangements should have been made to illustrate their action. 

 It is interesting to be told that a mysterious-looking combina- 

 tion of brass and steel, locked up in a glass box, can measure 

 the flight of a musket ball to the thirty- thousandth part of a 

 second, and the visitor may consider himself lucky that the 

 label tells him thus much, but far more ought to have been 

 done to make such objects understood. 



On the whole the Exhibition looks well for British skill and 

 taste — the chief exception being the management of the con- 

 cern itself, and we would suggest that the guilty parties should 

 be piled up in a " trophy," so as to show the inhabitants of all 

 countries the sort of people to whom such work ought not to 

 be confided when another opportunity comes round. 



ACAEI IN PHOTOGRAPHIC BATHS AND CHEMICAL 



SOLUTIONS 



In our report of the proceedings of the Microscopical Society, 

 the reader will see an account of 'the appearance of some acari 

 in a nitrate of silver bath employed for photographic purposes 

 by Dr. Maddox. The occurrence of such a form of life under 

 these singular, and, as might have been thought, fatal condi- 

 tions, calls to mind the experiments made many years ago by 

 Mr. Crosse, and which were ridiculously misrepresented in many 

 statements current then and since. The simple facts are re- 

 corded by Dr. Noad in the first volume of his Marmal of Eire - 

 tricity, from which we extract a few of the most important 

 particulars. In the course of his numerous experiments on 

 electro-crystallization, the philosopher of Broomfield operated 

 upon a solution of silicate of potash, which he supersaturated by 

 hydrochloric acid, and allowed to fall in drops upon a piece of 



