32 CLINICAL BACTERIOLOGY AND HEMATOLOGY 



of a clean handkerchief in strong spirit (absolute or rectified) and 

 wipe the slide with it, using a considerable amount of friction. 

 Now dry it with the special handkerchief mentioned above, heat 

 it thoroughly in a smokeless flame, and allow to cool completely. 

 Spread the film on the surface which was exposed directly to the 

 flame. 



Cover-glasses are cleaned in the method advised for slides, and 

 should be stored in strong alcohol smelling strongly of ammonia. 

 They are wiped with the special handkerchief immediately before 

 use. 



When cover-glasses are to be used for covering films spread 

 upon slides (as is generally the case if the method recommended 

 in this book is adopted) it is quite sufficient to wipe them carefully 

 with a clean handkerchief moistened with spirit, and then to dry 

 them. 



After slides or cover-glasses have been cleaned, the utmost care 

 must be taken that they do not come in contact with the skin, or 

 a thin film of grease will be deposited upon them. 



PIPETTES 



Glass pipettes for the collection of pathological fluid for 

 bacteriological examination are very frequently required. They are 

 readily made from a piece of quill glass tubing, and a few should 

 always be kept in stock against emergencies. 



One form consists of a bulb about | inch long, each end of 

 which is drawn out into a narrow tube at least 5 inches long, 

 tapering gradually to the extremities (Fig. 14, a). To make such 

 a pipette, take a piece of glass tubing about 6 inches long and a 

 J inch wide, and heat it in a luminous gas flame at a point ^ inch 

 or so from the centre. Continue the heat until the glass is 

 thoroughly softened over at least J inch of its length, turning 

 the tube round all the time ; then remove it from the flame 

 and draw the two ends apart with a steady, uniform pull, so 

 that the heated portion draws out into a capillary tube several 

 inches in length. Repeat the process at a point about J inch 

 from the tapering end of the larger portion of the tube ; heat the 

 bulb, and then seal off both ends of the capillary portion before 

 the bulb cools. 



The pipettes are necessarily sterile, having been drawn out of 

 partially melted glass, and they will remain sterile indefinitely. 



