KREATININ AND OTHER SUBSTANCES. 



40I 



It 



260. KREATININ AND OTHER SUBSTANCES. Kreatinin C 4 H 9 N 3 2 is 

 derived from the kreatin of muscle by the removal of a molecule of water, and partly 

 from flesh food. The quantity excreted daily is 0*6 to 1*3 gramme (8 to 18 

 grains). 



It is diminished in progressive muscular atrophy, tetanus, anaemia, marasmus, chlorosis, 

 consumption, paralysis ; and is increased in typhus, inflammation of the lung ; it is absent 

 from the urine of sucklings. 



Properties. Kreatinin is alkalkie, easily soluble in water and hot alcohol. It forms colour- 

 less oblique rhombic columns ; unites with acids and salts, silver nitrate, mercuric chloride, 

 and especially with zinc chloride. Kreatinin-zinc chloride (fig. 257) is used to detect its pres- 

 ence. Weyl's Test. Add to urine a few drops of a slightly brownish solution of nitro-prusside 

 of soda, and then weak caustic soda solution, producing a Burgundy-red colour, which soon 

 disappears. When heated with glacial acetic acid, the colour changes to green, which after a 

 time changes to blue (Salkoivski). [The blue colour Berlin blue is due to the formation of an 

 iron-salt ferro-cyanide of sodium from the decomposition of the nitro-prusside. The reaction 

 also succeeds with formic acid instead of glacial acetic acid if some time be allowed to elapse 

 after Weyl's reaction.] 



Xanthin = C 5 H 4 N 4 2 occurs only to the amount of 1 gramme in 300 kilos, of urine, 

 substance intermediate between sarkin 

 and uric acid. Guanin and hypoxan- 

 thin may be changed into xanthin ; in 

 contact with water and ferments it passes 

 into uric acid. When evaporated with 

 nitric acid, it gives a yellow stain, which 

 becomes yellowish-red on adding potash, 

 and violet-red on applying more heat. 

 It is an amorphous, yellowish-white 

 powder, fairly soluble in boiling water. 

 It has also been found in traces in 

 muscles, brain, liver, spleen, pancreas, 

 and thymus. The crystalline body 

 paraxanthin (dimethylxanthin) and the 

 amorphous heteroxanthin (methylxan- 

 thin) occur in traces in the urine (Salo- 

 mon). 



Sarkin or Hypoxanthin, C 5 H 4 N 4 0. 

 As yet this substance has been found 

 only in the urine of leukemic patients 

 (Jakubasch), and it has been prepared 

 in the form of needles or flattened scales 

 from muscle, spleen, thymus, brain, Yi& 257 - 



bone, liver, and kidney. In normal Kreatinin . zinc chloride< , ball^ith radiating marks : 

 urine a body nearly related to and pos- crvst allised from water ; c, from alcohol, 



sibly identical with, hypoxanthin occurs ' J ' ' 



(E. Salkowski). Hypoxanthin closely resembles xanthin, and can be changed into it by oxida- 

 tion. Nascent hydrogen, on the other hand, reduces uric acid to xanthin and hypoxanthin. 

 When evaporated with nitric acid it gives a light yellow stain, which becomes deeper, but not 

 reddish -yellow, on adding caustic soda. It is more easily soluble in water than xanthin, and 

 by this means the two substances can be separated from each other. Guanin is insoluble in 

 water. 



Oxaluric acid (CgH^N^C^) occurs in very small quantity combined with ammonia in urine. 

 Physiologically, it is interesting on account of its relation to uric acid. It is a white powder 

 slightly soluble in water. Ammonia oxalurate can be prepared from uric acid. 



Oxalic Acid (C 2 H 2 4 ) occurs, but not constantly, to the amount of 20 milli- 

 grammes daily as oxalate of lime, which is known by the " envelope " shape of 

 the crystals (fig. 258) ; insoluble in acetic acid, and forming transparent octahedra. 

 More rarely it assumes a biscuit or sand-glass form. The genetic relation of oxalic 

 acid to uric acid is shown by the fact, that dogs fed with uric acid excrete much 

 oxalate of lime. Oxalic acid may also be produced by the oxidation of products 

 derived from the fatty acid series (p. 381). 



Oxaluria. The eating of substances containing oxalate of lime (rhubarb) increases the excretion. 

 Increased excretion is called oxaluria ; it is regarded as a sign of retarded metabolism (Beneke), 

 and it may give rise to the formation of a calculus. In oxaluria the uric acid is also often in. 



2 c 



