CHAP. I.] PRESENCE OF SULPHOCYANATES IN SALIVA. 19 



Mode of de- (a) Human saliva is treated with a small volume of 

 monstrating a pale and acidulated solution of ferric chloride. A 

 presence of a reddish colouration of varying intensity, but tending to 

 that of diluted claret > is generally produced. This 

 colour is bleached by the subsequent addition of a 

 solution of corrosive sublimate. 



(6) According to Gscheidlen's l method, filter-paper is dipped in 

 a weak solution of ferric chloride containing some free hydrochloric 

 acid and then allowed to dry. The contact of a drop of saliva with 

 such paper occasions a reddish stain. The author can strongly 

 recommend this method. 



(c) Soleras Reaction. When human saliva is treated with a 

 solution of iodic acid it assumes a yellowish colour, due, according to 

 Solera 2 , only to the sulphocyanate present, which liberates iodine; 

 the latter is subsequently easily detected by the addition of starch. 

 This reaction is said to permit of the detection of 00000004 grm. of 

 a sulphocyanate. 



is a suipho- A sulphocyanate is not constantly present even in 

 cyanate con- human saliva. According to Hoppe-Seyler, with whose 

 itiy pre- ex p er i ence on this matter that of .the author does not 

 sent in saliva ? i . i i <* , i i , < T ^i i 



coincide, it is indeed frequently absent . In the saliva 



of the dog Hoppe-Seyler has never discovered a sulphocyanate, 

 whilst both Schiff and Solera discovered it in the mixed saliva and 

 in the secretion of the parotid gland. 



It has been asserted by Schiff that the quantity of a sulpho- 

 cyanate, as determined by the depth of tint produced by the addition 

 of an iron salt, increases after saliva has been secreted, but the state- 

 ment appears to be inaccurate. 



Proportion According to Munk 4 , whose method of quantitative 



of suiphocy- analysis will be described in a subsequent section of 

 anic acid in this chapter, the proportion of sulphocyanic acid in 

 mixed human saliva amounts to O'Ol per cent. 



and^probawe Sulphocyanic acid jj[S has a constitution exactly 



origin of sul- _.. 



analogous to that of cyanic acid - I 0, sulphur occu- 



pying the position of the oxygen of the latter body. 



In the metabolic decomposition of the proteids the chief nitro- 



1 Gscheidlen, ' Rhodannachweis ' Privatmittheilung. Maly's Jahresbericht, Vol. 

 iv. p. 91 ; also consult Gscheidlen, 'Ueber das constante Vorkommen einer Schwefel- 

 cyanverbindmig im Harn der Saugethiere.' Pfluger's Archiv, Vol. 14 (1877), p. 403. 



- Solera, ' Di una particolare reazione della saliva ' abstracted in Maly's Jahres- 

 bericht, Vol. vn. p. 256. ' Indagini sulle manifestazioni objettive del solfocyanuro 

 potassico salivare.' Pavia, 1877. Abstracted in Maly's Jahresbericht, Vol. vin. p. 235. 



3 Hoppe-Seyler, 'Bei weitem nicht alle Menschen haben schwefelcyanhaltigen 

 Speichel.' Physiologische Chemie, Part n. p. 186. 



4 J. Munk, ' Schwefelcyanbestimmung im Speichel.' Virchow's Archiv, Vol. LXIX. 

 p. 350. 



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