A Simple and Inexpensive Universal Pipet Bulb The u w cjf rohlar pipet bdhs ha, Img hcen a+-oc,sttd utrhvarilluc pnhlem>. inc.uding raic ut rwtrtd, hull, r~mt-imln:tllun,uir w r h variable rllnmrtpr piper;, and sterili,bhlllt). A \!nlple d e w e i, described herein which eliminates these problems.' It has been introduced into the undergraduate laboratories a t Middlebury College with great success and is favored by students over the commercially available atomizer and valve-type bulbs since it is easier to use. It seems also to have eliminated the tendency to pipet by mouth. It consists of a piece of black, thick-wall rubber tubing, 25 mm ID X 3.2 mm wall, cut to a length of 11-12 cm. Into one end is inserted a solid #6 rubber stopper, and into the other end is inserted a #6 stopper with one hole which is beueied.The result is an easily made pipet bulb which costs only about $0.90 and satisfies all of the common objections found with other bulbs (see figure). To draw up liquid, the beveled bulb opening need only be touched with slight pressure to the pipet thus eliminating the nuisance of getting the bulb off of the pipet in order to control the liquid level with the fingertip. It will accept any pipet with an OD greater than 4 rnm and less than 10 mm. Contamination of the pipet bulb, a majur problem in undergraduatelaborstories,is easily dealt with since bothstoppers can be removed and the contaminating liquid removed by washing. The inside of the tubing can be dried and the entire unit reassembled in a matter of minutes. Since all materials are of heat resistant rubber t h r ~ b u 1 1 ~ ~ s a o t o r l r ( \'~rtu.dly ~ ~ I 1 l ~ . d n y w l w m m3y hcdrnun up intt ~ h r p ~ pwith e t t h i hull, r n . thr piprt is nl~i ~ ~ Ihd id crpelling the air in
