Bauhaus-Universität Weimar

Handbook for the Physiological Laboratory. Text
Burdon-Sanderson, John Scott E. Klein Michael Foster T. Lauder Brunton
and is dissolved by excess of acid. 5. Alum precipitates chon- 
drin ; excess dissolves it. 6. Lead acetate, 7, Silver nitrate, 
8, Chlorine water, all precipitate chondrin. 
Effect of Boiling,—Boil a watery solution of chondrin for a 
long time. Let it cool, and it will be found to have lost its 
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 by 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. 
Th^ earthy salts are tribasic calcium, and magnesium 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 acid, bone 
gives out C02 and is apt to separate into lamellae. 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 they 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


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