Fig. Plate Page

1. I. Laboratory autoclave with stirrer . . Frontispiece

2. Sulphonating pot for naphthalene sulphonic acid . . 5

3. Fusion pot for β-naphthol ...... 8

4. Autogeneously welded sulphonating pot for use with oleum, etc. . . . . . . . . 11

5. Apparatus with propeller stirrer for reductions by

Bechamp-Brimmeyr method . . . . 17

6. II. Sulphonating and nitrating pot in wooden tub . . (12)

7. II. Steam-jacketed sulphonating and nitrating pot . . (12)

8. III. Hydraulic press ......... (24)

9. Heating under reflux condenser with stirring . . 47

10. IV. Nitrating pot with helical stirrer ..... (38)

11. IV. Reduction pot with propeller stirrer . . . . (38)

12. V. Separating funnel and extracting vessel . . . (52)

13. V. Centrifuge with underneath drive .... (52)

14. VI. Stone vacuum filter for strongly acid precipitates . . (62)

15. VI. Frame filter for crystalline precipitates .... (62)

16. Small gas cylinder for adding alkyl chloride ... 74 16a . Method of filling a laboratory autoclave with alkyl chloride 75 17. Apparatus for distilling in superheated steam . . 81 18. Witt's Bell-stirrer....... 84

18a. Heating under a reflex condenser and stirring with an ordinary bulb condenser ..... 84

19. Large-scale apparatus for distilling with superheated steam ......... 99

20. VII. Arrangement of a colour shed .... (76-77)

21. Calibrated vessel for coupling . . . . .112

22. Laboratory vacuum filter or "nutsch" . . .114

23

24 VIII. Autoclaves for steam or hot-water heating (Frederking) . . . (90)

25.

25A IX. Kubierschky columns. . . . . . (102)

26. IX. Raschig column ........ (102)

27. Laboratory vacuum distillation . . . .191

28. X. Works plant for vacuum distillation . . . .(112)

29. XI. Oil-jacketed autoclave for stiff melts . . . .(126)

30. XI. Section of autoclave ....... (126)

31. XII. Large cast-iron autoclave with steam heating . . (138)

32. XII. Large cast-steel autoclave ..... (138)

33. XIII. Stirring autoclave of Plate I. taken apart . . .(150)

34. Section through a laboratory autoclave . 199

35. XIV. Small cast-steel autoclave ...... (164)

36. XIV. Small cast-iron autoclave with stirrer .... (164)

37. XV. Wrought-iron rotating autoclave . . . . . (178)

38. Section through rotating autoclave . . . .201 38a. Details of rotating autoclave . . . . 201

39. Diagram of a "Perplex" disintegrator . 217

40. XVI. Passburg drying chest . . . . . . .(188)

41. XVI. Rotary compressor and vacuum pump . . . . (188)

42. XVII. Disintegrator for colours ...... (208)

43. Distillation of high-boiling liquid 227

44. XVIII. Colour mixing machine (Hoechst system) . . . (214)

45. XIX. Screw-press ........ (224)