Home » Methods and Techniques » Particles Size Separation by Pipette Method


Particles Size Separation by Pipette Method


The purpose of this method is to determine the quantity of each of the main sand, silt, and clay fractions in samples of soil form each horizon of the soil profile. A 2-m (#10) sieve will be used to separate the gravel (particles coarser than 2-mm) from the grains less than 2-mm in diameter and the percent sand will be isolated by wet sieving through a set of nested sieves. The silts and clays in each sample will be determine by using a (1) pipette that measures weight percent of sample or (2) a hydrometer that measure the density of a solution of silt and clay suspended in water.


The settling method is based on Stokes’ Law. This law states that denser (larger, usually) particles sink farther than less dense (smaller) particles when suspended in a liquid. There are two critical assumptions: (1) the particles all have the same density and (2) the particles are spherical. Actually, neither of these assumptions can be perfectly satisfied.

The pipette method measures the actual percent by weight of each particle size class in your sample. The hydrometer method uses the density of the soil/water mixture. The more particles that are in suspension at any one time, the more dense the soil/water mixture will be; the more dense the mixture, the better it will support an object placed in the mixture. That is, the more dense the mixture, the higher the hydrometer will float in the soil/water mixture. As larger mineral particles fall from suspension, the density of the soil/water mixture decreases. As the density decreases, the hydrometer sinks farther into the mixture. The stem of the hydrometer is marked in grams of sediment remaining in suspension.

In each method, after n seconds have elapsed from the time the soil/water mixture is thoroughly mixed (usually 40 seconds), all particles of one size will have fallen below a certain level in the suspension. After 6 hours and 52 minutes, all the silt (.05-. 002mm) will have fallen below this level, and only clay (less than .002mm) remains in suspension. The hydrometer reading (corrected) at 6 hours and 52 minutes will be a measure of the amount of clay remaining in suspension. From this hydrometer reading, and the initial total weigh of the sample, you will be able to calculate the proportion of the sample that is clay. The proportion of silt is the difference between the calculated percent clay and remaining silt & clay percent after the sands were removed.


Source: http://www.geology.iupui.edu/research/SoilsLab/procedures/psd/

Download a good ebook



  1. Shishir Kumar Sarker says:

    good job Tania…thanks

  2. Shahanur Shakil says:


  3. Labiba Farhana says:

    Great .. it’s helpful for class work ..

Post a Comment

You must be logged in to post a comment.


Recent Post

Hacked By Chinafans

Hacked By Chinafans Share this:TweetEmailPrint Related


Is there anyone to give right answer of these aassesment? I think You will be able to get the progress of Bangladesh in Flood controls and management shortly. To...

Issue of this week (21 August, 2016)

Issue of this week (21 August, 2016)

site de rencontre pour promener son chien prostitute how to site de rencontre cv prostituee et mst club rencontre solo rencontre edarling jeu virtuel gratuit de...


Very Good News for Bangladesh!!

It has been published in a daily newspaper that about 16 sq. km land is emerging every year in the coastal area of Bangladesh (Source: Prothom Alo, 05 August, 2016)....


Issue of this week

Coastal Tourism Potentiality in Bangladesh Bangladesh has a very beautiful coastal landscape. It can attract both local and foreign tourist. Do you think coastal...


Accidental Oil Pollution in the Sundarbans: Preparedness for Response to Ecological Disaster

Abstract: Sundarbans is the largest single mangrove forest of the world. This forest occupies near about 10,000 sq km of which Bangladesh includes about 6,000 sq....


Climate Change Induced Tropical Cyclone and Salinity Intrusion in the Sundarbans: An Impediment to the REDD Programs

Reducing Emissions from Deforestation and Forest Degradation in developing countries, or REDD for short, is a broad set of approaches and actions that will reduce...

The Suspended Sediment Loads of Ganges and Brahmaputra basin

The Suspended Sediment Loads of Ganges and Brahmaputra basin

prostituee villeparisis rencontre chaude kinshasa prostituees red dead redemption rencontre artisanal sombernon comment faire rencontre gratuite rencontres bd aix...

Modern sediment supply to the lower delta plain of the Ganges-Brahmaputra River in Bangladesh

Modern sediment supply to the lower delta plain of the Ganges-Brahmaputra River in Bangladesh

rencontres ellezelles prostituee reze centre recherche rencontre paris les dix commandements la rencontre ballouchi tunisie rencontre rencontre femme vallet rencontre...

Congratulations to Cricket Team of Geography and Environment

Congratulations to Cricket Team of Geography and Environment

We are very pleased to inform all our PG-DU.com members that, Geography and Environment department of University of Dhaka has finally got the “Inter-department...