Electrical, optical, acoustical, ultrasonic and/or laser scientific and laboratory instruments for counting, sizing, classifying, differentiating, and identifying particles in liquid or gases, for use in clinical, biological, industrial, medical, academic and/or scientific research and commercial laboratories, namely, particle size distribution and concentration measuring instruments, [ particle counting instruments, zeta potential measuring instruments, electrophoresis mobility measuring instruments, particle mobility measuring instruments, environmental temperature and humidity monitoring instruments, pH measuring instruments; instruments for producing zimm plots to determine the molecular weight of polymers namely, air and liquid particle counters, photocorrelation spectroscopy instruments, micro electrophoresis measuring instruments, acoustic spectroscopy instruments, ] laser diffraction measuring instruments, all for use in clinical, biological, industrial, medical, academic and/or scientific research and commercial laboratories; apparatus for preparing samples, suspensions, sprays, and emulsions of particles for use with any of the aforesaid goods, namely, sample dispersion units, stirred cells, autosamplers, dry powder feeders, dispensers, autotitrators, [ nebulizers, ] ultrasonic baths, and temperature controllers; computer and microprocessors, computer printers, computer software for controlling and operating all of the aforesaid goods; machine readable data carriers, namely, floppy discs, CD ROMs, optical discs, magnetic tapes, all packaged as a unit pre-programmed with control or analysis programs for use with the foregoing goods