74 VETEEINAEY TOXICOLOGY 



dead fowls gave | , grain phosphorus per ounce. After- 

 seven days' exposure the material in each case no longer 

 contained free phosphorus. After the phosphorus has 

 been fully oxidised to phosphoric acid its detection is 

 impossible, phosphates being normally present in ingesta 

 and organs. In the lower stages of oxidation the de- 

 tection is, briefly, as follows : (a) Act on the material with 

 zinc and dilute sulphuric acid, passing the gas through 

 silver nitrate solution. This yields a precipitate of silver 

 phosphide, [b) Collect the silver phosphide, and intro- 

 duce it into a hydrogen generating apparatus, passing the 

 hydrogen over solid caustic potash. The flame is green, 

 due to the presence of phosphoretted hydrogen (Dusart and 

 Blondlot). 



In this Way evidence is easily obtainable. For instance, 

 in a recently observed case no free phosphorus or lower 

 acid was found in the viscera of a dog ; and in the dried-up 

 vomit several daj's after emission no free phosphorus was 

 present, but lower acids were easily recognised. 



In medico-legal work no case of phosphorus poisoning 

 can be established unless either free phosphorus is found 

 in the ingesta or vomit, or failing this unless in the same 

 materials the lower acids are detected. The symptoms 

 and lesions must also be consistent with phosphorus 

 poisoning. It is hopeless to attempt to prove that the 

 quantity of phosphate is excessive, phosphates being found 

 in all animal matter, and in the case of the dog in 

 particular in large and variable amount on account of the 

 eating of bones. 



AMMONIA. 



Forms and Occurrence. — The only compounds of 

 ammonia of significance in toxicology are free ammonia 

 and ammonium carbonate. Free ammonia is encountered 

 in the form of the solution in water — the so-called 

 ammonium hydrate — or Uq2ior ammonice fortissimum, of 

 the Pharmacopoeia. It contains in concentrated condition 



