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