BY DR. LAUDER BRUNTOtf. 447 



power of gelatinizing, but it will give the other reactions just 

 as before. 



Decomposition of Chondrin. By boiling with concentrated 

 hydrochloric acid, chondrin is decomposed, and yields grape 

 sugar, and certain nitrogenous substances. The presence of 

 grape sugar may be tested by the reactions given in 77 

 or 155. 



51. Distinctive Characters of Mucin, Chondrin, 

 Gelatin, and Albumin. 



Mucin. Precipitated by acetic acid, the precipitate is not 

 dissolved by sodium sulphate. 



Chondrin. Precipitated by acetic acid, the precipitate is 

 dissolved \iy sodium sulphate. 



Gelatin. Not precipitated by acetic acid, nor by acetic acid 

 and potassium ferrocyanide. 



Albumin. Dissolved by acetic acid, the solution is precipi- 

 tated by potassium ferrocyanide, or by the-addition of 

 alkaline salts and heat. 



Gelatin and Chondrin are most generally recognized by their 

 hot solutions forming a jelly on cooling ; but as they are both 

 deprived of this property by long boiling or boiling with acids, 

 this test is not always to be depended on. 



** 52. Bone. When bone is subjected to the action of 

 acids, the earthy salts are removed. The remainder, to which 

 the name ossein has been given, consists chiefly of gelatigenous 

 substance. The earthy salts are tribasic calcium, and magne- 

 sium phosphates, calcium carbonate, and small quantities of 

 calcium fluoride. 



To remove the earthy salts, and leave the ossein, place a bone 

 for some time at a low temperature in very dilute hydrochloric 

 acid. When treated with warm dilute hydrochloric acrid, bone 

 gives out C0 2 and is apt to separate into lamella?. The ossein 

 is soft, flexible, and elastic while moist, but becomes hard 

 when dry. It retains the form of the bone. In its chemical 

 characters it resembles the gelatigenous substance from con- 

 nective tissue. 



To get the earthy salts, incinerate the bone, when the organic 

 substance will be consumed, and the}- will remain behind, mixed 

 with other salts formed during the combustion, for here as in 

 other cases the salts in the ash differ considerably from those 

 which exist in the tissue. 



** 53. Adipose Tissue. Fats. Fats differ from each 

 other in appearance and consistence. Their general properties 

 may be conveniently studied in olive oil, for which cod liver oil 

 or train oil may be substituted, if an animal fat is desired. 



Solubility. Fats are insoluble in 1. Water, and 2. Cold al- 

 cohol, f 3. Hot alcohol. Warm a test-tube containing oil 

 and alcohol over a spirit-lamp or Buuseii's burner. As the 



