128 ANATOMY AND PHYSIOLOGY. 



troduce a tube, and blow them up or inflate them. They suddenly 

 expand, change their color, and present a very imposing effectjJB 

 Every vessel but the trachea must be tied. 



In my popular lectures on Physiology and the reformed practiceS 

 I repeatedly tried this interesting experiment. The boy who in-^ 

 flated the lung used no tube, but put the end of the windpipe into 

 his mouth. His stomach was not very delicate. I have a model 

 in wax by the best artist of the lungs, in connexion with the heart, 

 which is extremely beautiful. 



The power of oxygen in supporting combustion, and of carbonic 

 acid in extinguishing it, should also be shown by introducing a 

 lighted candle, fixed to a wire, into jars of these gases. 



That the expired air contains carbonic acid, may easily be shown 

 by breathing through a tube immersed in newly prepared lime water. 

 The carbonic acid throws down the lime in the form of carbonate 

 of lime. 



By placing the ear to the upper part of the chest of a young per- 

 son, the murmur produced by the air rushing through the air- 

 vesicles may be heard ; or the stethoscope may be used for hearing 

 this, as well as the sounds of the heart. 



Preparations of the bronchial tubes are generally made by anato- 

 mists with wax. These, however, have the disadvantage of being 

 easily broken. There may be used, instead of wax, some of the 

 metals. Equal parts of tin and lead answer well for the larger 

 bronchi. Take a sheep's lungs, clear away fat, &c., but taking 

 care not to injure them, and cut off the windpipe three or four 

 inches above the lungs ; dry the interior of the windpipe by BRro- 

 ducing pieces of lint on the end of a stick, and afterwards allowing it 

 to remain exposed to the air for a few hours. Then transfix the 

 windpipe at the upper part with two darning-needles crossed, to 

 hang the lungs by ; fasten the needles to the ring of a retort-stand ; 

 fasten a wide-mouthed tin funnel, supported by another ring of the 

 retort, in the windpipe, and pour in the melted metal ; boil the 

 lungs for two hours, cut out the preparation, and varnish with wax 

 dissolved in boiling spirits of wine. A much more delicate pre- 

 paration can be made in the following manner : Instead of tin and 

 lead, take the composition called the fusible metal ,* and pour it into 

 the lungs, and then place these in a large pot of water, to be kept 

 boiling for an hour. The air is thus, in a measure, expelled ; and 



* The Fusibk Metal may be composed of two parts bismuth, one lead, one tin, and 

 one quicksilver, to be all melted together and well mixed. 



