| 摘要 |
1389494 Drop delivering apparatus UNILEVER Ltd 9 May 1973 [11 May 1972] 22140/72 Heading B8N [Also in Divisions C6 F1 and G2] Series of agar droplets of varying dilutions arranged on a Petri dish, are examined for microbial growth by placing the dish over a point source lamp 3, Fig. 1, and viewing the magnified image in a ground glass screen 8. The light travels to the screen through an objective lens 5, an angled reflecting prism 6 and a front surfaced mirror 7. The droplets are produced as follows: solenoid actuated pump 10, see Fig. 2, of stroke capacity 1À0 ml. sucks in agar into a pipette (not shown) held in a holder connected to line 14. Solenoid actuated pump 11 of stroke capacity 0À1 ml. draws in air through a system of one-way valves 12 and on the return stroke ejects the air into the pipette whereby a 0À1 ml. drop is dispensed on to a Petri dish (not shown). When a sample row containing say, 5 such drops has been delivered, a further drop may be ejected into 9-10 ml. of diluent and the sequence repeated in respect of the 1/100 diluted agar. If desired the hole contents of the pipette may be ejected into diluent. The solenoids may be actuated by press-button switches. |
