American journal of physiology . s by means of lead cotton, a method which Haber-mann (11) employed in identifying hydrogen sulphide in tobaccosmoke. This method consists in drawing the liberated gas through aglass tube containing dry absorbent cotton which has previously beensoaked in neutral solution of lead acetate, and dried. A Ladenburg Liberation of Volatile Sulphide from Milk on Heating. 455 flask (Fig. 2, a) of three hundred cubic centimetres capacity is con-nected with a glass tube {p) which contains the lead cotton. Toprevent condensation water from entering this tube a bulb {/) issu
American journal of physiology . s by means of lead cotton, a method which Haber-mann (11) employed in identifying hydrogen sulphide in tobaccosmoke. This method consists in drawing the liberated gas through aglass tube containing dry absorbent cotton which has previously beensoaked in neutral solution of lead acetate, and dried. A Ladenburg Liberation of Volatile Sulphide from Milk on Heating. 455 flask (Fig. 2, a) of three hundred cubic centimetres capacity is con-nected with a glass tube {p) which contains the lead cotton. Toprevent condensation water from entering this tube a bulb {/) issuspended between the flask and tube. As in the previous method,the passage of the gas through the tube is facilitated by cautiousaspiration. In order to regulate the current of air, the latter is bubbledthrough a wash bottle containing water {d) which is placed betweenthe cotton tube and the suction pump. The air drawn through themilk is made to pass through a wash bottle {e) containing a strongsolution of potassium (V^^ Figure 2. Two hundred cubic centimetres of milk are introduced into theflask, and the latter plunged into a boiling water-bath. Within fiveminutes the lead cotton begins to blacken. In ten minutes an in-tensely black band is seen in the tube. The intensity and width ofthe band increases with the heating, so that after forty-five to fiftyminutes the band in the small tube is fully half an inch broad. By far the greater part of the blackening occurs within the firsthour, while at the end of the second hour there is little change. Thisis a very satisfactory method for qualitative study, and is also of valuein making comparative studies of different samples of milk, the in-tensity of the blackening and the width of the band affording anindication as to the amount of sulphide liberated. Pasteurized and condensed milk deport themselves peculiarlytowards heat, the amount of sulphide liberated being much smallerthan with normal milk. Different samples of
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