On the Benzoic Acid in the Urine of Horses. 1 5 1 



pound of pot or pearl ashes ; pour the clear lye into the 

 boilino-pan; add a sufficient quantity of water thereto that 

 Av'ill cover the yarn about four inches ; light the fire, and 

 enter the yarn, when the liquor is a little warm ; observe 

 to keep it constantly under the liquor for two hours ; in- 

 crease the heat regularly till it come to a scald ; then take 

 the yarn out, wash it, and hang it to dry as in former ope- 

 rations. 



Seventh Operation. 



Make a sour liquor of oil of vitriol and water ; the de- 

 n'ree ef acidity may be a little less than the juice of lemons ; 

 fay the yarn m it tor about an hour, then take it out, wash 

 it very well and wring it; give it a second washing and 

 wringins:, and lay it on a board. 



■ N. B."" This operation is to dissolve the metallic particles, 

 and remove the ferruginous matter that remains on the sur- 

 face of the thread after the fifth opertion. 



Eighth Operation. 



For every ten pounds of yarn dissolve one pound of best 

 ^vhite soap in clear water, and add as much water to this 

 liquor in your boiling-pan as will be sufficient to boil the 

 varn for tuo hours. When these liquors are well mixed- 

 hcht the fire, enter the yarn, and bring the liquor to boil 

 hr about an hour. Continue it boiling slowly an hour; 

 take it out, wash it in clear water very well, and hang it tor 

 dry as in former operations : when dry it is ready for the 

 weaver. 



N.B. It appears to me, from experiments that I have 

 hiade, that less than four operations in the preparation of 

 the yarn will not be sufficient to cleanse the pores of the 

 fibres of the cotton, and render the colour permanent. 



XXIII. On the Benzoic Acid in the Urine of Horses. Bij 

 A/. Ferdinand GiESE, of Berlin*. 



According to the researches of Fourcroy and Vauqueliri 

 on the urine of ditl'erent graminivorous animals, the benzoic 

 acid at all times forms a component part of it. Partly \yith 

 a view to place this beyond a doubt, and partly that I might 

 accurately deterniine the proportion which this substance 

 bears to the other component parts, I made the following 



• From Sthcrcr's Allgnneims Jourml dcr Cbcmie, no. 41. 



K. 4 c.xperi*- 



