PROTEINS 

 I. TYPICAL l'l ITEIN I -. . . ALBUMIN i. 



tullv pour the white iif an egg into an evaporating 



dish. i In- \.-lks; they will he collected hy the instructor. 



This i- an approximate!} u'. -olntion of a protein (albumin). 



it- viscous con-i-teiicv. < ihserve that it ran he drawn out 



into rather long cords () r cylinder-; compare with water in this 



;>ecl. Test the reaction with litmus paper; is it acid, alkaline. 

 or neutral: < >f one-half of the egg-white make a 10' , -olmion. To 



this, place in an evaporating dish and cut the egg-white freely 

 with the scissors; this liU-rates it fnun the nieiuhranes. Then mix 

 with nine times its volume of water, stirring thoroughly. A pre- 

 cipitate of glohuliu. another protein, forms. Kilter through several 

 told* of wet linen. Keep the undiluted half for further u>e. 



\. Co VGULATION. 



39. ( "iif/nliition />y heat. Have a water-hath with water at 



hoiling temperature. I'm some of the undiluted egg-white and the 



HP', egg-white in tcst-tuhe- and place in the water-hath. Which 



lll Ics lir-t ': \\hai conclusion can he drawn as to the ettcct 



of dilution on coagulation hy luat : 



Coagulation />v chemicals. To 5 cc, of the i<>', solution add 

 a few dnp~ ,.f ^', copper sulphate. Note the coagulation. I'. sing 

 a new -pccimen of solution ti<>', i at each trial, try in the -ame 

 way mercuric chloride- and lead acetate, recording results. Trv 

 also strong nitric, hydrochloric, and sulphuric acids, in the follow- 

 ing wax : allow a drop or two of the acid to run down the >ide 

 of the tuhe till it reaches the -olmion. Tr\ also <,;', alcohol, picric 

 acid, tannic arid, phosphotungstic acid, and l\,l ; eii \ i,. adding first 

 a little dilute acetic acid in the case of the la-t four reagent-. 



ji Manner in rc/nr/i cinifinlatian takes / 1 /./ l -< > . 1 >ip a thin thread 

 ot silk in a $' , s.,lmion of copper sul]ihate and lav the thread on a 

 ^la-- sljdi . hi-iieath a cover glass. Allow s,, n ie of the K>', solution 

 Jiite of , gg !,, ,- un under the cover .ula-- while olerving the 

 operalinii with the micro-rope i high |>oweri. The alhnmin ahotit 

 the tlmad will hi- -i-en to form -mall granule-, appearing like a 

 tint- cloud, and the-e later run together lo form an open network. 



A i ille of t w- 111 tin- pi i id 



< in M n \i. i ii VK vi i i ui-i n - 



I 'lace a little powdered dry alhu- 

 i the hoitoni of a d> v t<--t -tuhe. and in-ert at the mouth of 



n 



