824 SEC. 18. BIOLOGY. 



3820. Biological Specimens, six bottles. 



Professor Rollcston, F.R.S., Oxford University Museum. 



3820a. Collection of Entomological Preparations for the 

 Microscope, comprising dissections of insects and whole insects, 

 mounted in Canada balsam. Frederic Enoch. 



Some of these preparations are mounted in a deep cell, and by being treated 

 in a peculiar manner their natural form is preserved, and the internal structure 

 of muscles and tarchese seen in their natural positions. 



3821. Objects exhibited by Professor Moser. 



The geometrical and perspective drawings, I., II., and III., represent an 

 apparatus for the determination of the products of the respiration and per- 

 spiration of animals. The apparatus is arranged at the I. K. Chemico- 

 Agricultural Experimental Institution at Vienna, for experiments on horses, 

 cattle, sheep, and pigs, The plan is that of Professor M. Pettenkofer, of 

 Munich, excepting that for the aspiration of the air, which is the same as 

 that adopted in a smaller apparatus by Professor C. Voit, of Munich. The 

 parts are as follows : 



A, chamber for the reception of the animal during the experiment. 



B, tube of tin, for the passage of the gaseous products from the chamber. 



C, a vessel jn which the gaseous products are saturated with watery 

 vapour. 



D, a gasometer in which the volume of the gases is determined. 



E, tube through which the measured gases escape. 



F, engine (hot air) which, by turning the revolving drum of the gasometer 

 aspirates the gases through the parts A, D, and, as a consequence, draws fresh 

 air in through the openings in the back of A'. 



To ascertain the quantities of carbonic acid, aqueous vapour, and methan 

 (marsh gas) evolved by the animal, the composition both of the gases 

 passing from the chamber A through the tube B and of the fresh air is 

 determined, Avith regard to their contents of these substances, and the difference 

 show.s the quantities of the gases evolved. 



For these examinations the apparatus shown on the table G is employed. 

 Aspirating and forcing pumps (c, c, c,) which close with mercury, draw small 

 quantities either of air from B through the tubes a, a, ...or of fresh air through 

 the tubes b, 6,... and force them through the absorption apparatus d, d,.., 

 and d\ y dl, or rf2, d2, to the gasometers e, c, ,... where they are measured. 



The motion of the pumps is effected by the engine F by means of the 

 mechanism o, p, q, r, s. To every absorption apparatus there appertain 

 two pumps which alternately aspirate and force, and four valves with mercury 

 joints (/,/,/...). 



The carbonic acid is absorbed by a test solution of baryta in the tubes d d 

 ...and <*!,</!.... 



The aqueous vapour is determined in the flasks d2, d2,... which contain 

 pumice stone saturated with sulphuric acid. 



The carburetted hydrogen is oxidated by passing over ignited oxide of 

 copper. For this purpose a portion of the air to be analysed is drawn by 

 the pumps through the tubes y, g, filled with oxide of copper, and placed upon 

 a furnace H. The products of the oxidation, carbonic acid and water, are 

 then conveyed to the absorption apparatus and gasometers. 



The drawing IV. represents a similar apparatus, but of smaller dimensions, 

 which also is employed at the I. K. Chemico-Agricultural Expermental Insti- 

 tution at Vienna. Its construction is in the main the same, excepting that 

 th ventilation is effected by the exhausting fanner K. The motion of K 



